According to data from the 1989 Soviet census, the population of the USSR was made up of 70% East Slavs, 17% Turkic peoples, with no other single ethnic group making up more than 2%. Alongside the atheist majority of 60%, there were sizable minorities of Russian Orthodox Christians and Muslims.

The 1989 Soviet census, conducted between 12 and 19 January of that year, was the final census carried out in the Soviet Union. The census found the total population to be 286,730,819 inhabitants. In 1989, the Soviet Union ranked as the third most populous in the world, above the United States, although it was well below China and India.