A simple ceremony was held in the snow at Smolensk in western Russia, at the site of the plane crash exactly two years ago that killed a Polish president and 95 others.
The Polish culture minister travelled to Russia with families of some of the victims. The tragedy affected the whole Polish nation, he said, and would continue to be felt deeply for many years.
But the calm, sombre mood of the occasion belied ongoing anger and division over what caused the crash.
Both Polish and Russian investigations blamed pilot error and bad weather, with the Poles saying that Russian air controllers were also at fault.
In Warsaw several hundred supporters of the opposition Law and Justice Party gathered outside the presidential palace to hold their own rival commemorations to the official ceremonies.
The party leader Jaroslaw Kaczynski – the dead president’s brother – disputes the findings of the official inquiries and has now said he believes that the crash was an assassination.
A minority of Poles back conspiracy theories saying the crash was no accident – but that the Russians downed the plane because of Kaczynski’s criticisms of Moscow’s foreign policy.