The article reviews the life and work of an outstanding Russian pharmacologist Professor Nikolai Kravkov (1865-1924). Among his many scientific achievements, he worked on an extract from the pancreas of animals in the early 1920s and was successful in isolating the internal secretion, which he named "pancreotoxine." This reduced blood glucose levels in animals and diabetic humans. Kravkov's work on the isolation of pancreotoxine was going on coincidentally with F. Banting's and C. Best's research of insulin, but their methods of isolation of the hormone were quite different.