The purges, in which an estimated 40 million people were killed, began in the summer of 1937.
Mostly elderly relatives of victims laid flowers and lit candles at a memorial stone from northern Russia's Solovetsky prison camp.
Sergei Volkov, chairman of the Russian Association of Victims of Political Repression, told RFE/RL's Russian Service that "not a single top official" came to lay flowers at the monument, which is located in front of the Federal Security Service's Moscow headquarters.
"There's a law [in Russia] on the rehabilitation of the victims of political repressions that was drafted by us, by public organizations, and was adopted and signed in 1991 by President [Boris] Yeltsin," Volkov said. "It states clearly that the state recognizes its guilt. Today, for some reason, nobody talks about it."
Yury Brodsky, director of a museum of the victims of political repressions at Solovki on the Solovetsky Islands, said it has become increasingly difficult to gain access to archives about the purges in recent years.
"I don't even know if Putin is to blame for that. Maybe it's the people around him," Brodsky told RFE/RL. "Until a proper assessment of what happened is made, we won't be able to develop further, and there is always a possibility of recurrence of what happened in one form or another."
Today's gathering in Moscow was organized by the Moscow Association for the Victims of Illegal Purges.