The illness and death of Mozart are reviewed, citing sources from his diary and letters to his family, as well as eyewitness accounts by persons present at his final illness. From these and other documentary evidence given by his personal physician, a reasonable adn logical retrospective diagnosis can be made given modern medical knowledge. The long-held popular belief that Mozart died of heavy-metal poisoning is re-assessed in the light of these findings. There is no medical ground for accepting the 'poison hypothesis'. I believe that Mozart was a victim of common bacterial infections--notably streptoccal, that were prevalent in 18th-century Europe. The immunological sequelae of repeated streptococcal infections on the kidneys and their complications are the most likely cause of the composer's death.