| Game |
| Result | Moves |
Year | Event/Locale | Opening |
| 26. J Kostro vs H Koskinen |
| ½-½ | 73 | 1958 | Munich Olympiad Final-B | B16 Caro-Kann, Bronstein-Larsen Variation |
| 27. H Koskinen vs B De Greiff |
| ½-½ | 17 | 1958 | Munich Olympiad Final-B | B31 Sicilian, Rossolimo Variation |
| 28. I Bilek vs H Koskinen |
| 1-0 | 55 | 1958 | Munich Olympiad Final-B | D78 Neo-Grunfeld, 6.O-O c6 |
| 29. E Arnlind vs H Koskinen |
| ½-½ | 19 | 1958 | Munich Olympiad Final-B | B16 Caro-Kann, Bronstein-Larsen Variation |
| 30. H Koskinen vs A Gudmundsson |
| ½-½ | 19 | 1958 | Munich Olympiad Final-B | B30 Sicilian |
| 31. H Koskinen vs L Ljungquist |
| ½-½ | 32 | 1958 | Jonkoping 1958/59 | B28 Sicilian, O'Kelly Variation |
| 32. H Koskinen vs Kotov |
| 0-1 | 38 | 1958 | Jonkoping 1958/59 | B06 Robatsch |
| 33. K Lindman vs H Koskinen |
| 0-1 | 37 | 1958 | Jonkoping 1958/59 | B16 Caro-Kann, Bronstein-Larsen Variation |
| 34. H Ek vs H Koskinen |
| ½-½ | 41 | 1958 | Jonkoping 1958/59 | D83 Grunfeld, Grunfeld Gambit |
| 35. H Koskinen vs Z Nilsson |
| 1-0 | 65 | 1959 | Jonkoping 1958/59 | C99 Ruy Lopez, Closed, Chigorin, 12...cd |
| 36. H Koskinen vs O Barda |
| ½-½ | 35 | 1959 | Jonkoping 1958/59 | B28 Sicilian, O'Kelly Variation |
| 37. H Enevoldsen vs H Koskinen |
| ½-½ | 21 | 1959 | Jonkoping 1958/59 | D68 Queen's Gambit Declined, Orthodox Defense, Classical |
| 38. M Lilliestrom vs H Koskinen |
| ½-½ | 28 | 1959 | Jonkoping 1958/59 | A48 King's Indian |
| 39. Ragozin vs H Koskinen |
| 1-0 | 22 | 1959 | Jonkoping 1958/59 | D86 Grunfeld, Exchange |
| 40. H Koskinen vs H Liebert |
| ½-½ | 42 | 1968 | Lugano Olympiad qual-6 | B04 Alekhine's Defense, Modern |
| 41. E Roebuck vs H Koskinen |
| 0-1 | 43 | 1968 | Lugano Olympiad qual-6 | B12 Caro-Kann Defense |
| 42. H Koskinen vs A Nejjar |
| 1-0 | 38 | 1968 | Lugano Olympiad qual-6 | C04 French, Tarrasch, Guimard Main line |
| 43. H Koskinen vs K Skold |
| ½-½ | 65 | 1968 | Lugano Olympiad qual-6 | C87 Ruy Lopez |
| 44. H Koskinen vs J Rodriguez Gonzalez |
| ½-½ | 20 | 1968 | Lugano Olympiad Final-B | B31 Sicilian, Rossolimo Variation |
| 45. F Visier Segovia vs H Koskinen |
| ½-½ | 66 | 1968 | Lugano Olympiad Final-B | D93 Grunfeld, with Bf4 & e3 |
| 46. H Koskinen vs M J Freeman |
| 1-0 | 23 | 1968 | Lugano Olympiad Final-B | B49 Sicilian, Taimanov Variation |
| 47. B Thorsteinsson vs H Koskinen |
| ½-½ | 12 | 1968 | Lugano Olympiad Final-B | B16 Caro-Kann, Bronstein-Larsen Variation |
| 48. H Koskinen vs S Kagan |
| 0-1 | 35 | 1968 | Lugano Olympiad Final-B | B11 Caro-Kann, Two Knights, 3...Bg4 |
| 49. R Beyen vs H Koskinen |
| ½-½ | 33 | 1968 | Lugano Olympiad Final-B | D98 Grunfeld, Russian |
| 50. J Kupper vs H Koskinen |
| ½-½ | 22 | 1968 | Lugano Olympiad Final-B | B10 Caro-Kann |
Kibitzing
