Serge Abrahamovitch Voronoff (Russian: Сергей Абрамович Воронов; c. July 10, 1866 – September 3, 1951) was a French surgeon of Russian extraction who gained fame for his technique of grafting monkey testicle tissue on to the testicles of men for purportedly therapeutic purposes while working in France in the 1920s and 1930s. The technique brought him a great deal of money, although he was already independently wealthy. As his work fell out of favour, he went from being highly respected to a subject of ridicule. Other doctors, and the public at large, quickly distanced themselves from Voronoff, pretending they had never had any interest in the grafting techniques. By the time of his death in 1951 at the age of 85, few newspapers noted his passing, and those that did acted as if Voronoff had always been ridiculed for his beliefs. In 1999, some speculated that the AIDS virus discovered in the 1980s entered the human population through Voronoff's transfer of monkey parts into humans in the 1920s. Presently, however, his efforts and reputation have been somewhat rehabilitated.