In post-Soviet Russia, the Jewish Diaspora was rapidly shrinking under the influence of negative natural population growth, emigration and assimilation. It was good education, high social status and westernization of the Jews that contributed to a decrease in the birth rate, development of assimilation and mass emigration of Jews to the West and to Israel. The exodus of Jews from post-Soviet Russia led to negative elements slowly accumulating over the last century, within 25 years after the collapse of the USSR, reached a critical mass and placed the Diaspora as an ethnic unit on the brink of survival. To assess the state of the Diaspora in recent years, materials from the all-Russian censuses of 2002 and 2010 and also the sociological survey of 2017, which captured 235 St. Petersburg Jews, have been used.