| Game |
| Result | Moves |
Year | Event/Locale | Opening |
| 26. J van Mil vs R W O'Brien |
| ½-½ | 13 | 1982 | Regency Masters | C40 King's Knight Opening |
| 27. A Muir vs R W O'Brien |
| 1-0 | 37 | 1982 | Regency Masters | D20 Queen's Gambit Accepted |
| 28. R W O'Brien vs Plaskett |
| ½-½ | 13 | 1982 | Regency Masters | E18 Queen's Indian, Old Main line, 7.Nc3 |
| 29. K Arkell vs R W O'Brien |
| 1-0 | 28 | 1982 | Regency Masters | B14 Caro-Kann, Panov-Botvinnik Attack |
| 30. R W O'Brien vs M A Pagden |
| 1-0 | 29 | 1982 | Regency Masters | E62 King's Indian, Fianchetto |
| 31. I Bilek vs R W O'Brien |
| 1-0 | 33 | 1983 | Benedictine International | D34 Queen's Gambit Declined, Tarrasch |
| 32. R W O'Brien vs R Hartoch |
| 0-1 | 21 | 1983 | Regency Masters | D10 Queen's Gambit Declined Slav |
| 33. R W O'Brien vs G Crawley |
| 0-1 | 46 | 1984 | Regency Masters | C89 Ruy Lopez, Marshall |
| 34. J Levitt vs R W O'Brien |
| 1-0 | 18 | 1985 | Guernsey Open | E20 Nimzo-Indian |
| 35. S W Giddins vs R W O'Brien |
| 1-0 | 24 | 1991 | Hastings Challengers 1991/92 | E67 King's Indian, Fianchetto |
| 36. M Hennigan vs R W O'Brien |
| 1-0 | 60 | 1994 | British Championship | A07 King's Indian Attack |
| 37. R D de Coverly vs R W O'Brien |
| ½-½ | 23 | 1994 | British Championship | D00 Queen's Pawn Game |
| 38. R W O'Brien vs K Chakraborty |
| 1-0 | 52 | 1995 | Hastings Centenary Masters | A49 King's Indian, Fianchetto without c4 |
| 39. R W O'Brien vs D J James |
| ½-½ | 10 | 1995 | Hastings Centenary Masters | E18 Queen's Indian, Old Main line, 7.Nc3 |
| 40. L Cooper vs R W O'Brien |
| 1-0 | 24 | 1995 | Hastings Centenary Masters | B14 Caro-Kann, Panov-Botvinnik Attack |
| 41. J Menadue vs R W O'Brien |
| 1-0 | 32 | 1995 | Hastings Centenary Masters | D50 Queen's Gambit Declined |
| 42. R W O'Brien vs P Roberts |
| ½-½ | 44 | 1995 | Hastings Centenary Masters | A85 Dutch, with c4 & Nc3 |
| 43. A Lewis vs R W O'Brien |
| 1-0 | 65 | 1995 | Hastings Centenary Masters | A43 Old Benoni |
| 44. R Muskath vs R W O'Brien |
| ½-½ | 22 | 1995 | Hastings Centenary Masters | D55 Queen's Gambit Declined |
| 45. R W O'Brien vs F Deketelaere |
| ½-½ | 15 | 1995 | Hastings Centenary Masters | C01 French, Exchange |
| 46. E Keogh vs R W O'Brien |
| 1-0 | 31 | 1996 | IRL-ch | C26 Vienna |
| 47. R W O'Brien vs S J Pullinger |
| ½-½ | 19 | 1997 | St Helier op | D07 Queen's Gambit Declined, Chigorin Defense |
| 48. D Oates vs R W O'Brien |
| 1-0 | 19 | 1998 | Hampstead Open 4th | A39 English, Symmetrical, Main line with d4 |
| 49. R W O'Brien vs C Deva |
| ½-½ | 41 | 1998 | Hampstead Open 4th | B50 Sicilian |
| 50. R Cannon vs R W O'Brien |
| ½-½ | 12 | 1998 | Hampstead Open 4th | C27 Vienna Game |
Kibitzing
