President Dmitry Medvedev awarded state honors to Oleg Skripochka, Mikhail Korniyenko and Alexander Skvortsov, crewmembers of the last two expeditions to the International Space Station, bestowing the title Hero of Russia, the country's highest decoration, RIA Novosti reported.
Veteran Soviet cosmonauts Alexei Leonov, the first man to walk in space, and Valentina Tereshkova, the first woman in space, were given the prestigious Order of Friendship.
In marking the anniversary of the first manned flight into space, Medvedev described Gagarin's 108-minute flight in a Vostok-1 capsule as a "revolutionary event" that changed the world.
Meanwhile, a crowd gathered near the Volga river at a memorial marking the exact spot where Gagarin parachuted to earth 50 years ago after his historic flight.
"When I first heard that a man had flown to space, I didn't believe it," said Yury Alexandrovich, 71, who came to the festivities at the memorial and said he was working nearby when Gagarin landed. "The news came through that he'd landed close by and we got in the car and came to see if it was true, and there he was in a space suit. It was like a fairytale."
The concrete memorial sees annual celebrations and the occasional wedding, RIA Novosti reported.
The celebration was bittersweet for some who attended.
"Gagarin is a symbol of how much potential our country once had and we are proud to celebrate that," Alexander Yakovlev, a mechanic who traveled 300 miles to attend the ceremony, said. "We will never achieve anything like that again."