Police estimated 90,000 joined the march, The Moscow Times reported. A similar event last year, six days before Putin was inaugurated, attracted a crowd of 150,000.
City officials said 14 other rallies were held in Moscow to mark May Day, now known as Spring and Labor Day. About 5,000 joined a Communist Party march, carrying signs with portraits of Marx, Engels and Lenin and slogans like "Hands off the glorious history of the Soviet Union!" and "Our goal is updated socialism."
St. Petersburg's May Day rally was the largest in the country, RIA Novosti reported. It was sponsored by a coalition of trade unions and drew 150,000 people, who marched down the Nevsky Prospect, the grand boulevard designed by Peter the Great.
In Chechnya, about 120,000 people joined a rally in Grozny, the capital, organizers said.
Police promised tight security for May Day and the following week, ITAR-Tass reported.