A Surgeon’s Unusual Quest
In the early 20th century, Serge Voronoff, a French surgeon of Russian origin, made headlines across Europe. Having trained under Nobel Prize-winning scientist Alexis Carrel, Voronoff specialized in transplants—but not just any kind.
By 1920, he was grafting thin slices of monkey testicle tissue onto human testicles, claiming it could restore youth, strength, and vitality.
From Animal Trials to Human Operations
Before operating on humans, Voronoff performed over 500 transplants on animals. He grafted young animal testicles onto old goats, sheep, and bulls, reporting increased vigor and strength.
In June 1920, he conducted his first human monkey gland graft, inserting tiny sections of chimpanzee or baboon tissue into the scrotum of elderly men. The procedure soon attracted men from all over the world, and by the early 1930s, over 500 patients in France had undergone the surgery, with many more treated internationally.
Global Fame and a Monkey Farm
Voronoff’s procedures gained so much popularity that he established his own monkey farm in Ventimiglia, Italy, to supply tissue. High-profile figures, including industrialist Harold McCormick, sought his surgeries. His wealth soared, and his clinic attracted media attention, curious scientists, and celebrities.
Despite the skepticism from parts of the medical community, Voronoff maintained a busy schedule, performing surgeries and writing books like Rejuvenation by Grafting in 1925.
The Scientific Downfall
As medical science advanced, skepticism grew. By the late 1930s and 1940s, evidence showed that transplanted animal tissue was rejected by the human body, producing no real physiological effects. Surgeons concluded that any improvements were due to placebo.
Voronoff’s methods fell out of favor, and he became a subject of ridicule. Still, his work left a lasting historical mark as one of the most bizarre chapters in transplant research.
In the 1920s, Serge Voronoff became famous worldwide for transplanting monkey testicle tissue into men, claiming it restored youth and vitality.
Patients came from around the world, eager to undergo his daring and controversial procedures…🧵👇 pic.twitter.com/XqRsaMMK6T
— Detective Tiger's Stories (@TigerDetective) July 19, 2025