More than 50 world leaders, including US President George W Bush, have been paying tribute in Moscow to the Soviet people's sacrifice in World War II.
Vladimir Putin stressed the Soviet Union's wartime sacrifice
A mass parade took place in Red Square - the latest in a series of events in Europe marking 60 years since the Allied victory over Nazi Germany.
The 75-minute commemoration was followed by the laying of wreaths at the tomb of the unknown soldier.
But the event has been overshadowed by disagreements over the war's legacy.
Despite the grey skies, Moscow's city centre was transformed into a sea of colour for the celebrations.
They began with four soldiers marching across Red Square with the Soviet victory flag, to the sounds of a military band. Thousands of servicemen bearing Red Army standards followed.
World leaders saluted as 2,500 frontline veterans were driven past in trucks, carrying red carnations.
Fighter jets flew over the square streaming red, white and blue smoke, the colours of the Russian tricolour flag.
Addressing the crowds, Russia's President Vladimir Putin stressed the extent of the Soviet sacrifice to save the world from the Nazis.
"For us the victory is the victory of all of us," he said, addressing the selected crowd attending the parade.
The world was "also aware that the Soviet Union lost dozens of millions of citizens over those years", he added.
"All the people of the Soviet Union suffered such losses that will never be repaired," he said.
"Thanks to the valiant elements of our army we repulsed the enemy," he said.
President Bush, the first US president to attend a Russian victory parade, earlier hailed the liberation from the Nazis, but said the Soviet occupation of Eastern Europe that followed was "one of the greatest wrongs of history".
More than 40 million people had lost their lives by the time World War II ended in Europe on 8 May 1945, including 27 million from the Soviet Union.
The ceremonies took place amid tight security.
Central Moscow was closed off and people encouraged to watch the commemoration on television, leading to complaints that the event was not for ordinary people.
World leaders attending included French President Jacques Chirac, Germany's Chancellor Gerhard Schroeder and Chinese President Hu Jintao.
UK Prime Minister Tony Blair, who is forming a new cabinet following his election victory, did not attend. Britain was represented by Deputy Prime Minister John Prescott.
Japanese Prime Minister Junichiro Koizumi also came, despite the absence of a treaty ending World War II hostilities between Moscow and Tokyo.
Polish President Aleksander Kwasniewski was at the parade, despite strong objections from many Poles who said he should not attend as the defeat of the Nazis in 1945 did not bring freedom to Poland.
The Soviet occupation of the Baltic states prompted Estonia and Lithuania to boycott Moscow's commemorations, which mark the signature of the unconditional surrender in Berlin.
They have demanded a fresh apology from Russia, but President Putin said it was not necessary, as the 1939 pact that effected the handover had already been criticised by Soviet-era authorities.
A Festival of Democracy is also under way in Germany, in a sign of reconciliation with past enemies and relief at the defeat of the Nazi dictatorship.