Abstract: The previously unpublished letters that Benjamin Fondane and his wife, Geneviève, sent to Boris de Schloezer (1881-1969) highlight their friendship with the Russian philosopher Léon Shestov. Boris de Schloezer was the main translator of Shestov’s works in French, who also played a major part in disseminating Shestov’s thought and establishing relationships with other intellectuals, such as Rachel Bespaloff and Jacques Schiffrin, the editor of the Pléiade collection at Gallimard. Most of the letters date back to the Second World War, either to the time when Fondane was a soldier in the French army and was trying to keep in touch with his friends after the defeat of 1940, or during the dark period of the Occupation, before the writer’s arrest and deportation. The last letter, sent in January 1944, provides a detailed escription of Fondane’s state of mind during the Nazi persecutions of Jews in Paris. Boris de Schloezer’s correspondence with Geneviève Fondane and Emil Cioran contains new information about the posthumous edition of Fondane’s work, Baudelaire et l’expérience du gouffre.