Tolush won the Leningrad Championship in 1937, 1938, 1946, and 1947 and played in the USSR Championship ten times. His best result was second place (+8=6−3 shared with Aroninand Lipnitsky) behind Keresin 1950. He finished fourth in 1952 (+8=7−4, equal with Boleslavskyand behind Botvinnik, Taimanov, and Geller) and fourth 1957 (+10=6−5 equal with Spassky and behind Tal,Bronstein, and Keres).
His best international result was first place (+10=8−1) at Bucharest 1953, ahead of Petrosian,Smyslov, Boleslavsky, and Spassky. Bucharest 1953 was the first informal foreign tournament, in which several Soviet chess players participated. The marathon lasted from 25 January to 27 February 1953. László Szabó took the lead during the first part of the tournament. The five Soviet players were on top at the end. Tolush gained the title of international grandmaster and his pupil Spassky became international master. In 1968 he was second at Keszthely +7=3−1 behind Portisch.Tolush represented the USSR in two European Team Chess Championship.
Although he never reached the very highest level of chess, Tolush was an imaginative attacking player. He worked as a chess journalist and was a noted trainer whose pupils included Keres and Spassky.
Though he was an outstanding master of attack, his play was never sound enough for the highest honors. He became a Soviet national master in 1938, served in the Red Army in WW II, then really blossomed.