A century and a half after the Black Death killed over a third of the population of Western Europe, a new plague swept across the continent. The Great Pox - commonly known as the French Disease - brought a different kind of horror: instead of killing its victims rapidly, it endured in their bodies for years, causing acute pain, disfigurement and ultimately an agonising death. The authors analyse the symptoms of the Great Pox and the identity of patients, richly documented in the records of the massive hospital of 'incurables' established in early sixteenth-century Rome. They show how the disease threw accepted medical theory and practice into confusion and provoked public disputations among university teachers. And at the most practical level they reveal the plight of its victims at all levels of society, from ecclesiastical lords to the poor who begged in the streets. Examining a range of contexts from princely courts and republics to university faculties, confraternities and hospitals, the authors argue powerfully for a historical understanding of the Great Pox based on contemporary perceptions rather than on a retrospective diagnosis of what later generations came to know as 'syphilis'.