Yakovlev was 82.
Russia's ITAR-TASS news agency says he died in Moscow today of an unspecified illness.
Yakovlev, who joined the Soviet Communist Party's ruling Politburo in 1987, spearheaded Gorbachev's drive to encourage liberalization of Soviet society and press freedom. He is considered by many as the intellectual father of Gorbachev's glasnost (openness) and perestroika (restructuring).
Yakovlev also played a key role in exposing past crimes of the Soviet regime.
He was critical of Russian President Vladimir Putin's restrictions on democracy.