In 1976, he finished fifth in Moscow in the 44th Soviet championship as Anatoly Karpov won by a full point over Yuri Balashov.

[1] One of his most emphatic victories occurred in qualification for this championship, at the 1976 First League tournament, where he finished 1½ points clear of the field (+6 =11).

In 1977, he was joint USSR Champion with Boris Gulko (both +4 =11, ahead of Petrosian, Polugaevsky and Tal).

He coached the French player Étienne Bacrot from age nine to Grandmaster level, when he became France's and the world's youngest ever.

In April 2019, Dorfman joined chess24 as one of the site's commentators and coaches together with Laurent Fressinet and Jean-Baptiste Mullon.