| 438-5 | Surrey v Glamorgan | The AMP Oval, Kennington | 2002 | a14362 |
| 386-3 | Surrey v Glamorgan | The Brit Oval, Kennington | 2010 | a20690 |
| 372-7 | Somerset v Glamorgan | The Cooper Associates County Ground, Taunton | 2018 | a26415 |
| 371-4 | Hampshire v Glamorgan | County Ground, Southampton | 1975 | a1477 |
| 368-4 | Somerset v Glamorgan | County Ground, Taunton | 2010 | a20758 |
| 360-3 | Somerset v Glamorgan | The Gnoll, Neath | 1990 | a6657 |
| 347-7 | Sussex v Glamorgan | The 1st Central County Ground, Hove | 2019 | a27374 |
| 341 | Kent v Glamorgan | St Helen's, Swansea | 2017 | a25576 |
| 341 | Essex v Glamorgan | The Cloud County Ground, Chelmsford | 2022 | a29370 |
| 340-5 | Northamptonshire v Glamorgan | Sophia Gardens, Cardiff | 2023 | a30169 |
| 338-3 | Somerset v Glamorgan | The SSE SWALEC Stadium, Cardiff | 2017 | a25533 |
| 337-9 | Worcestershire v Glamorgan | County Ground, New Road, Worcester | 2022 | a29419 |
| 332-2 | Kent v Glamorgan | Sophia Gardens, Cardiff | 2006 | a17477 |
| 332-6 | Hampshire v Glamorgan | The Ageas Bowl, Southampton | 2017 | a25570 |
| 331-7 | Warwickshire v Glamorgan | The Gnoll, Neath | 2023 | a30124 |
| 330-4 | Somerset v Glamorgan | Sophia Gardens, Cardiff | 1978 | a2237 |
| 327-9 | Pakistan A v Glamorgan | Spytty Park, Newport | 2016 | a24818 |
| 326-6 | West Indies A v Glamorgan | Eugene Cross Park, Ebbw Vale | 2006 | a17556 |
| 326-7 | Essex v Glamorgan | Sophia Gardens, Cardiff | 2019 | a27267 |
| 325-6 | Essex v Glamorgan | The Essex County Ground, Chelmsford | 2016 | a24835 |
| 323-3 | Sussex v Glamorgan | The Brighton and Hove Jobs County Ground, Hove | 2014 | a23502 |
| 322-7 | Somerset v Glamorgan | The Cooper Associates County Ground, Taunton | 2016 | a24832 |
| 317-7 | Kent v Glamorgan | The SSE SWALEC Stadium, Cardiff | 2015 | a24166 |
| 316-4 | Essex v Glamorgan | County Ground, Chelmsford | 2004 | a16124 |
| 316-5 | Hampshire v Glamorgan | St Helen's, Swansea | 2016 | a24848 |
| 312-8 | British Universities v Glamorgan | FP Fenner's Ground, Cambridge | 1996 | a9803 |
| 310-5 | Essex v Glamorgan | Southchurch Park, Southend-on-Sea | 1983 | a3756 |
| 310-7 | Hampshire v Glamorgan | The Rose Bowl, Southampton | 2006 | a17498 |
| 310-9 | Somerset v Glamorgan | County Ground, Taunton | 2007 | a18192 |
| 309-3 | Sri Lanka A v Glamorgan | Sophia Gardens, Cardiff | 2004 | a15980 |
| 307-2 | Durham v Glamorgan | Emirates Durham International Cricket Ground, Chester-le-Street | 2012 | a22083 |
| 307-8 | Surrey v Glamorgan | Woodbridge Road, Guildford | 2014 | a23427 |
| 305-9 | Durham v Glamorgan | Feethams Cricket Ground, Darlington | 1991 | a7089 |
| 304-6 | Middlesex v Glamorgan | Sophia Gardens, Cardiff | 2018 | a26424 |
| 304-8 | Kent v Glamorgan | Sophia Gardens, Cardiff | 2022 | a29319 |
| 303-9 | Essex v Glamorgan | County Ground, Chelmsford | 1997 | a10659 |
| 302-6 | Hampshire v Glamorgan | County Ground, Southampton | 1997 | a10604 |
| 302-9 | Sussex v Glamorgan | County Ground, Hove | 1998 | a11155 |
| 299-4 | Hampshire v Glamorgan | County Ground, Southampton | 1991 | a7002 |
| 298-5 | Essex v Glamorgan | County Ground, Chelmsford | 2003 | a15238 |
| 298-5 | Surrey v Glamorgan | Whitgift School, Croydon | 2003 | a15258 |
| 298-8 | Derbyshire v Glamorgan | The Incora County Ground, Derby | 2023 | a30114 |
| 298-7 | Somerset v Glamorgan | The Cooper Associates County Ground, Taunton | 2023 | a30162 |
| 297-6 | Essex v Glamorgan | The Ford County Ground, Chelmsford | 2009 | a19769 |
| 296-5 | Worcestershire v Glamorgan | County Ground, New Road, Worcester | 2010 | a20723 |
| 294-5 | Hampshire v Glamorgan | St Helen's, Swansea | 1983 | a3764 |
| 294-9 | Hampshire v Glamorgan | County Ground, Southampton | 1985 | a4405 |
| 294-7 | Middlesex v Glamorgan | The SSE SWALEC Stadium, Cardiff | 2016 | a24779 |
| 293-3 | Hampshire v Glamorgan | The Ageas Bowl, Southampton | 2019 | a27279 |
| 292-6 | Sussex v Glamorgan | The 1st Central County Ground, Hove | 2017 | a25517 |
| 291-5 | Leicestershire v Glamorgan | St Helen's, Swansea | 1984 | a4093 |
| 291-4 | Kent v Glamorgan | Mote Park, Maidstone | 2003 | a15192 |
| 291-5 | Leicestershire v Glamorgan | Penrhyn Avenue, Rhos-on-Sea, Colwyn Bay | 2008 | a19099 |
| 290-3 | Kent v Glamorgan | Spitfire Ground, St Lawrence, Canterbury | 2016 | a24773 |
| 289-5 | Essex v Glamorgan | Southchurch Park, Southend-on-Sea | 2000 | a12923 |
| 289-5 | Middlesex v Glamorgan | Lord's Cricket Ground, St John's Wood | 2019 | a27363 |
| 289 | Essex v Glamorgan | Sophia Gardens, Cardiff | 2021 | a28528 |
| 288-5 | Gloucestershire v Glamorgan | The SWALEC Stadium, Cardiff | 2013 | a22629 |
| 287-6 | Warwickshire v Glamorgan | Edgbaston, Birmingham | 1976 | a1722 |
| 287-5 | Middlesex v Glamorgan | Lord's Cricket Ground, St John's Wood | 1990 | a6679 |
| 286-3 | Hampshire v Glamorgan | County Ground, Southampton | 1989 | a6022 |
| 285-5 | Kent v Glamorgan | Sophia Gardens, Cardiff | 1987 | a5242 |
| 284-9 | Middlesex v Glamorgan | Sophia Gardens, Cardiff | 2005 | a16756 |
| 283-6 | Hampshire v Glamorgan | St Helen's, Swansea | 2007 | a18248 |
| 283-9 | Gloucestershire v Glamorgan | Penrhyn Avenue, Rhos-on-Sea, Colwyn Bay | 2007 | a18261 |
| 283-5 | Leicestershire v Glamorgan | Grace Road, Leicester | 2007 | a18380 |
| 282-7 | Northamptonshire v Glamorgan | Sophia Gardens, Cardiff | 2005 | a16830 |
| 281-6 | Nottinghamshire v Glamorgan | St Helen's, Swansea | 2011 | a21442 |
| 280-8 | Surrey v Glamorgan | The Brit Oval, Kennington | 2007 | a18359 |
| 280-9 | Essex v Glamorgan | The SSE SWALEC Stadium, Cardiff | 2017 | a25544 |
| 278-6 | Kent v Glamorgan | Spitfire Ground, St Lawrence, Canterbury | 2018 | a26435 |
| 277-8 | Sussex v Glamorgan | Sophia Gardens, Cardiff | 2018 | a26461 |
| 276-9 | Sussex v Glamorgan | The 1st Central County Ground, Hove | 2023 | a30138 |
| 275-6 | Worcestershire v Glamorgan | St Helen's, Swansea | 1987 | a5366 |
| 275-9 | Warwickshire v Glamorgan | Sophia Gardens, Cardiff | 2002 | a14576 |
| 275-3 | Lancashire v Glamorgan | Old Trafford, Manchester | 2010 | a20553 |
| 274-6 | Gloucestershire v Glamorgan | Sophia Gardens, Cardiff | 1999 | a12054 |
| 273-7 | Warwickshire v Glamorgan | Edgbaston, Birmingham | 2000 | a12871 |
| 273-3 | Worcestershire v Glamorgan | County Ground, New Road, Worcester | 2005 | a16751 |
| 272-7 | Hampshire v Glamorgan | St Helen's, Swansea | 1978 | a2167 |
| 271-8 | Durham v Glamorgan | Riverside Ground, Chester-le-Street | 2007 | a18385 |
| 270-3 | Somerset v Glamorgan | County Ground, Taunton | 2001 | a13597 |
| 269-9 | Kent v Glamorgan | Mote Park, Maidstone | 1986 | a4915 |
| 269-8 | Sussex v Glamorgan | County Ground, Hove | 1986 | a4932 |
| 269-5 | Surrey v Glamorgan | The Kia Oval, Kennington | 2018 | a26480 |
| 268-5 | Surrey v Glamorgan | The Foster's Oval, Kennington | 2000 | a12854 |
| 268-7 | Northamptonshire v Glamorgan | Penrhyn Avenue, Rhos-on-Sea, Colwyn Bay | 2009 | a19880 |
| 267-6 | Essex v Glamorgan | Sophia Gardens, Cardiff | 2003 | a15206 |
| 267-8 | Northamptonshire v Glamorgan | County Ground, Northampton | 2004 | a15986 |
| 266-8 | Warwickshire v Glamorgan | St Helen's, Swansea | 1966 | a69 |
| 265-8 | Kent v Glamorgan | St Helen's, Swansea | 1990 | a6541 |
| 265-9 | Hampshire v Glamorgan | The Rose Bowl, Southampton | 2006 | a17627 |
| 265-2 | Gloucestershire v Glamorgan | Sophia Gardens, Cardiff | 2018 | a26407 |
| 264-6 | Nottinghamshire v Glamorgan | Trent Bridge, Nottingham | 2012 | a22114 |
| 263-8 | Kent v Glamorgan | St Helen's, Swansea | 1992 | a7682 |
| 263-7 | Sussex v Glamorgan | Sophia Gardens, Cardiff | 1993 | a8031 |
| 263 | Middlesex v Glamorgan | Lord's Cricket Ground, St John's Wood | 1996 | a9835 |
| 263-7 | Gloucestershire v Glamorgan | County Ground, Bristol | 2005 | a16860 |
| 262-4 | Essex v Glamorgan | Southchurch Park, Southend-on-Sea | 1984 | a4118 |
| 262-4 | Worcestershire v Glamorgan | County Ground, New Road, Worcester | 1989 | a6079 |
| 262-5 | Northamptonshire v Glamorgan | Wardown Park, Luton | 1992 | a7631 |
| 262-8 | Middlesex v Glamorgan | Lord's Cricket Ground, St John's Wood | 2007 | a18202 |
| 261-8 | Dorset v Glamorgan | St Helen's, Swansea | 1990 | a6609 |
| 261-8 | Warwickshire v Glamorgan | Sophia Gardens, Cardiff | 2002 | a14277 |
| 261-9 | Somerset v Glamorgan | Sophia Gardens, Cardiff | 2019 | a27295 |
| 260-4 | Middlesex v Glamorgan | Lord's Cricket Ground, St John's Wood | 2004 | a15911 |
| 259 | Lancashire v Glamorgan | Penrhyn Avenue, Rhos-on-Sea, Colwyn Bay | 2011 | a21481 |
| 259 | Surrey v Glamorgan | Sophia Gardens, Cardiff | 2019 | a27338 |
| 258-7 | Somerset v Glamorgan | Westlands Sports Ground, Yeovil | 1977 | a1947 |
| 258-7 | Sussex v Glamorgan | County Ground, Hove | 1980 | a2742 |
| 258-7 | Somerset v Glamorgan | County Ground, Taunton | 1986 | a4829 |
| 258-9 | Somerset v Glamorgan | County Ground, Taunton | 1997 | a10462 |
| 258-9 | Hampshire v Glamorgan | County Ground, Southampton | 2000 | a12895 |
| 257-9 | Somerset v Glamorgan | County Ground, Taunton | 1999 | a12109 |
| 257-8 | Sussex v Glamorgan | Sophia Gardens, Cardiff | 2006 | a17431 |
| 257 | Yorkshire v Glamorgan | Penrhyn Avenue, Rhos-on-Sea, Colwyn Bay | 2013 | a22601 |
| 257 | Gloucestershire v Glamorgan | County Ground, Bristol | 2019 | a27347 |
| 257-9 | Yorkshire v Glamorgan | Sophia Gardens, Cardiff | 2022 | a29349 |
| 256-7 | Lancashire v Glamorgan | Old Trafford, Manchester | 2006 | a17615 |
| 256-6 | Worcestershire v Glamorgan | The SWALEC Stadium, Cardiff | 2010 | a20568 |
| 255-4 | Kent v Glamorgan | St Lawrence Ground, Canterbury | 1980 | a2763 |
| 255-2 | Middlesex v Glamorgan | Lord's Cricket Ground, St John's Wood | 2015 | a24221 |
| 254-8 | Surrey v Glamorgan | The Foster's Oval, Kennington | 1989 | a6175 |
| 254-7 | Northamptonshire v Glamorgan | County Ground, Northampton | 1991 | a7145 |
| 254-3 | Middlesex v Glamorgan | The SWALEC Stadium, Cardiff | 2009 | a19895 |
| 254-9 | Middlesex v Glamorgan | Lord's Cricket Ground, St John's Wood | 2013 | a22607 |
| 253-4 | Yorkshire v Glamorgan | Headingley, Leeds | 1991 | a7106 |
| 253-9 | Worcestershire v Glamorgan | Sophia Gardens, Cardiff | 1996 | a9916 |
| 253-6 | Middlesex v Glamorgan | Sophia Gardens, Cardiff | 1998 | a11169 |
| 251 | Hampshire v Glamorgan | May's Bounty, Basingstoke | 1974 | a1280 |
| 251-4 | Sussex v Glamorgan | Central Recreation Ground, Hastings | 1982 | a3355 |
| 251 | Derbyshire v Glamorgan | Four Trees, Checkley | 1991 | a7167 |
| 251-9 | Derbyshire v Glamorgan | County Ground, Derby | 1995 | a9351 |
| 251-7 | Essex v Glamorgan | County Ground, Chelmsford | 1996 | a9950 |
| 251-3 | Derbyshire v Glamorgan | Sophia Gardens, Cardiff | 2003 | a15134 |
| 251-7 | Somerset v Glamorgan | County Ground, Taunton | 2012 | a22066 |
| 251-8 | Gloucestershire v Glamorgan | County Ground, Bristol | 2013 | a22783 |
