| Game |
| Result | Moves |
Year | Event/Locale | Opening |
| 26. M Castillo vs C H Maderna |
| 1-0 | 32 | 1934 | South American Championship 1934/35 | D30 Queen's Gambit Declined |
| 27. M Castillo vs J M Cristia |
| 1-0 | 24 | 1934 | South American Championship 1934/35 | D09 Queen's Gambit Declined, Albin Counter Gambit, 5.g3 |
| 28. I Pleci vs M Castillo |
| 1-0 | 52 | 1934 | South American Championship 1934/35 | D55 Queen's Gambit Declined |
| 29. L Piazzini vs M Castillo |
| ½-½ | 48 | 1934 | South American Championship 1934/35 | D70 Neo-Grunfeld Defense |
| 30. C Pulcherio vs M Castillo |
| ½-½ | 21 | 1934 | South American Championship 1934/35 | D41 Queen's Gambit Declined, Semi-Tarrasch |
| 31. M Castillo vs L Palau |
| 1-0 | 40 | 1934 | South American Championship 1934/35 | D51 Queen's Gambit Declined |
| 32. M Castillo vs J C Balparda |
| ½-½ | 66 | 1934 | South American Championship 1934/35 | D51 Queen's Gambit Declined |
| 33. M Castillo vs J Vinuesa |
| ½-½ | 49 | 1934 | South American Championship 1934/35 | D55 Queen's Gambit Declined |
| 34. R Grau vs M Castillo |
| 1-0 | 40 | 1934 | South American Championship 1934/35 | D74 Neo-Grunfeld, 6.cd Nxd5, 7.O-O |
| 35. C Hounie Fleurquin vs M Castillo |
 | 1-0 | 20 | 1934 | South American Championship 1934/35 | B02 Alekhine's Defense |
| 36. M Castillo vs J Molina |
| ½-½ | 36 | 1934 | South American Championship 1934/35 | B32 Sicilian |
| 37. M Castillo vs C Guimard |
| 0-1 | 34 | 1934 | South American Championship 1934/35 | D37 Queen's Gambit Declined |
| 38. M Castillo vs J Bolbochan |
| ½-½ | 31 | 1936 | Mar del Plata | D13 Queen's Gambit Declined Slav, Exchange Variation |
| 39. R Flores Alvarez vs M Castillo |
| ½-½ | 30 | 1936 | Mar del Plata | C48 Four Knights |
| 40. M Castillo vs V Fenoglio |
| ½-½ | 65 | 1936 | Mar del Plata | B12 Caro-Kann Defense |
| 41. C Guimard vs M Castillo |
| 1-0 | 27 | 1936 | Mar del Plata | A84 Dutch |
| 42. M Castillo vs Letelier |
| ½-½ | 44 | 1936 | Mar del Plata | D85 Grunfeld |
| 43. A Pons vs M Castillo |
| 0-1 | 32 | 1936 | Mar del Plata | B23 Sicilian, Closed |
| 44. M Castillo vs C Hounie Fleurquin |
| 1-0 | 28 | 1936 | Mar del Plata | D21 Queen's Gambit Accepted |
| 45. R Charlier vs M Castillo |
| ½-½ | 31 | 1936 | Mar del Plata | D32 Queen's Gambit Declined, Tarrasch |
| 46. M Castillo vs L Piazzini |
| ½-½ | 36 | 1936 | Mar del Plata | D24 Queen's Gambit Accepted |
| 47. M Castillo vs J Vinuesa |
| 0-1 | 58 | 1936 | Mar del Plata | E76 King's Indian, Four Pawns Attack |
| 48. B H Villegas vs M Castillo |
| ½-½ | 50 | 1936 | Mar del Plata | A09 Reti Opening |
| 49. M Castillo vs J C Balparda |
| ½-½ | 30 | 1936 | Mar del Plata | D02 Queen's Pawn Game |
| 50. I Pleci vs M Castillo |
| ½-½ | 74 | 1936 | Mar del Plata | D31 Queen's Gambit Declined |
Kibitzing
