Per World Chess Federation (FIDE), his highest numerical Elo rating was 2437 which he reached in January 2001 up to July 2001.
[3] At the 1st Burroughs Computers Grandmasters Tournament held from April 5–19, 1978 at New Zealand, Mascariñas tied for third place with a score of 7/12 posting 4 wins, 6 draws and 2 losses just behind tournament winner Miguel Quinteros (10/12) and countryman Eugene Torre (8/12) and tied with Ortvin Sarapu.
[citation needed] Mascariñas also played at the 29th (2001) Annual World Open held in Philadelphia, USA, a 9-round Swiss System event featuring 228 players.
[5][6][7] He played in eight Chess Olympiads (1976, 1978, 1980, 1982, 1984, 1988, 1990, 1992) garnering a total score of 46.5 points/82 games on the strength of 26 wins, 41 draws and 15 losses.
[10] In 1988 at the 28th Chess Olympiad held at Thessaloniki, Greece, he was part of Team Philippines that recorded a best-ever 7th-place finish manning Board 2.