One of the ancestors of the family, after the destruction of the autonomy of the Cossack Hetmanate in 1764, to receive a parish, had to change his original Ukrainian surname Okhrimenko to the Russian Yefremov (Okhrim – Yefrem).

[2] Serhiy Yefremov was born in the village of Palchik, Petrykivka Volost Zvenigorodka uezd of the Kyiv Governorate.

Political activity started during student years becoming the member of the Ukrainian Universal non-Party Democratic Organization.

He was arrested numerous times by the Russian authorities for pressing public speeches in defense of national culture and political freedoms in pre-revolutionary period.

He was the chief defendant in the 1929 public show trial of the leaders of the supposed Union for the Liberation of Ukraine.