There is dispute about the cause of Beethoven's death; alcoholic cirrhosis, syphilis, infectious hepatitis, lead poisoning, sarcoidosis and Whipple's disease have all been proposed. In this article all primary source documents related to Beethoven's terminal illness and death are reviewed. The documents include his letters, the report of his physician Andreas Wawruch, his Conversation Books, the autopsy report, and a new toxicological report of his hair. His terminal illness was characterised by jaundice, ascites, ankle oedema and abdominal pain. The autopsy data indicate that Beethoven had cirrhosis of the liver, and probably also renal papillary necrosis, pancreatitis and possibly diabetes mellitus. His lifestyle for at least the final decade of his life indicated that he overindulged in alcohol in the form of wine. Alcohol was by far the most common cause of cirrhosis at that period. Toxicological analysis of his hair showed that the level of lead was elevated. During the eighteenth and early nineteenth centuries, lead was added illegally to inexpensive wines to sweeten and refresh them. These findings strongly suggest that liver failure secondary to alcoholic cirrhosis, associated with terminal spontaneous bacterial peritonitis, was the cause of death. This was complicated in the end stages by renal failure. If the presence of endogenous lead was verified by analysis of Beethoven's skeletal remains, it would suggest that the lead was derived from wine that he drank. Lead poisoning may account for some of his end-of-life symptoms. There is little clinical or autopsy evidence that Beethoven suffered from syphilis.