Boris Ephrussi (Russian: Борис Самойлович Эфрусси; 9 May 1901 – 2 May 1979), Professor of Genetics at the University of Paris, was a Russo-French geneticist. Boris was born on 9 May 1901 into a Jewish family. His father, Samuel Osipovich Ephrussi, was a chemical engineer; his grandfather, Joseph Ephrusi (Efrusi), was the founder of a banking dynasty in Kishinev. He published two papers in November 1966 which represented a key step in a decade of research in his laboratory. This research helped transform mammalian, and especially human, genetics.