| Game |
| Result | Moves |
Year |
Event/Locale | Opening |
| 1. H MacGrillen vs D A MacDaeid |
 | 0-1 | 27 |
1965 |
IRL-ch | A93 Dutch, Stonewall, Botvinnik Variation |
| 2. H MacGrillen vs P Hohler |
| ½-½ | 33 |
1966 |
Orebro Stud olm prelim4 | E12 Queen's Indian |
| 3. T Bjornsson vs H MacGrillen |
| 1-0 | 40 |
1966 |
Orebro Stud olm fB | E88 King's Indian, Samisch, Orthodox, 7.d5 c6 |
| 4. H MacGrillen vs D Rivera |
| 1-0 | 43 |
1966 |
Orebro Stud olm fB | A21 English |
| 5. H MacGrillen vs S Kagan |
| ½-½ | 40 |
1966 |
Orebro Stud olm prelim4 | E98 King's Indian, Orthodox, Taimanov, 9.Ne1 |
| 6. H MacGrillen vs Krantz |
| 0-1 | 25 |
1966 |
Orebro Stud olm fB | A70 Benoni, Classical with 7.Nf3 |
| 7. J Rodriguez Cordoba vs H MacGrillen |
| ½-½ | 18 |
1966 |
Orebro Stud olm fB | D42 Queen's Gambit Declined, Semi-Tarrasch, 7.Bd3 |
| 8. J Verstraeten vs H MacGrillen |
| ½-½ | 16 |
1966 |
Orebro Stud olm fB | B09 Pirc, Austrian Attack |
| 9. H MacGrillen vs P Hohler |
| 0-1 | 36 |
1966 |
Orebro Stud olm fB | C95 Ruy Lopez, Closed, Breyer |
| 10. H MacGrillen vs P Jamieson |
| 0-1 | 57 |
1966 |
Orebro Stud olm fB | A54 Old Indian, Ukrainian Variation, 4.Nf3 |
| 11. P N Lee vs H MacGrillen |
| 1-0 | 33 |
1966 |
Orebro Stud olm prelim4 | C95 Ruy Lopez, Closed, Breyer |
| 12. S Bouaziz vs H MacGrillen |
| 1-0 | 41 |
1966 |
Orebro Stud olm fB | E62 King's Indian, Fianchetto |
| 13. O Seuss vs H MacGrillen |
| 0-1 | 47 |
1968 |
WchT U26 15th fin-B | C91 Ruy Lopez, Closed |
| 14. M Moe vs H MacGrillen |
| ½-½ | 21 |
1968 |
WchT U26 15th qual-D | C27 Vienna Game |
| 15. H MacGrillen vs G Israel |
| ½-½ | 34 |
1968 |
WchT U26 15th fin-B | E99 King's Indian, Orthodox, Taimanov |
| 16. D Levy vs H MacGrillen |
 | 0-1 | 49 |
1968 |
WchT U26 15th fin-B | C45 Scotch Game |
| 17. B Kristjansson vs H MacGrillen |
| ½-½ | 23 |
1968 |
WchT U26 15th qual-D | C96 Ruy Lopez, Closed |
| 18. H MacGrillen vs L Holmstrand |
| 1-0 | 40 |
1968 |
WchT U26 15th qual-D | D25 Queen's Gambit Accepted |
| 19. N Skalkotas vs H MacGrillen |
| 0-1 | 26 |
1968 |
WchT U26 15th fin-B | E28 Nimzo-Indian, Samisch Variation |
| 20. H MacGrillen vs A Zwaig |
| ½-½ | 44 |
1968 |
WchT U26 15th fin-B | A56 Benoni Defense |
| 21. H MacGrillen vs Keene |
  | 0-1 | 61 |
1968 |
Student Olympiad | E45 Nimzo-Indian, 4.e3, Bronstein (Byrne) Variation |
| 22. F Saboya vs H MacGrillen |
| ½-½ | 19 |
1968 |
WchT U26 15th fin-B | E50 Nimzo-Indian, 4.e3 O-O 5.Nf3, without ...d5 |
| 23. H MacGrillen vs T Porrasmaa |
| ½-½ | 16 |
1968 |
WchT U26 15th fin-B | E91 King's Indian |
| 24. E Eichhorn vs H MacGrillen |
| ½-½ | 27 |
1968 |
WchT U26 15th fin-B | C84 Ruy Lopez, Closed |
| 25. H MacGrillen vs A J Whiteley |
| ½-½ | 48 |
1968 |
WchT U26 15th fin-B | D48 Queen's Gambit Declined Semi-Slav, Meran |