Albert Léon Charles Calmette was the first person to develop an anti-venom serum. His work revolutionized the treatment of snakebite in men and domestic animals. He is also well known for his development of the Bacillus Calmette-Guérin (BCG) vaccine for the prevention of tuberculosis. This article reviews the life experiences of this pioneer bioscientist, the current status of BCG in preventing tuberculosis, and the potential of BCG in immunotherapy for cancer.