The paleopathological study of 40 Italian Renaissance mummies has allowed us to perform about 20 diagnoses, of which 5 concern infectious (smallpox, hepatitis, condyloma, syphilis and pneumonia), 4 metabolic (obesity, atherosclerosis, gallstones and uric acid nephrolithiasis), 2 articular (DISH and rheumatoid arthritis) and 2 neoplastic (skin apithelioma and colon adenocarcinoma) diseases. The mummy of an anonymous child, dated back to the 16th century (C14=1569 +/- 60), presented a diffuse vesiculo-pustular exanthema. Macroscopic aspects and regional distribution suggested smallpox, while EM reavealed many egg-shaped, virus-like particles (250 x 50 nm), with a central dense core. Following incubation with anti-smallpox virus antiserum and protein A-gold complex immunostaining, the particles resulted completely covered with protein A-gold. These results clearly show that this Neapolitan child died of a severe form of smallpox some four centuries ago. The mummy of Maria of Aragon, Marquise of Vasto (1503-1568), reavealed on the left arm an oval, cutaneous ulcer (15x10 nm) with linen dressing. Indirect immunofluorescence with anti-treponema pallidum antibody identified a large number of filaments with the morphological characteristics of fluorescent treponemes. EM evidenced typical spirochetes, with axial fibril. These findings clearly demonstrate a treponemal, probably venereal, infection. The mummy of Ferrante I of Aragon, King of Naples (1431-1494), revealed an adenocarcinoma extensively infiltrating the muscles of the small pelvis. A molecular study of the neoplastic tissue evidenced a typical mutation of the K-ras gene codon 12:the normal sequence GGT (glycine) was altered into GAT (aspartic acid). At present this genetic change is the most frequent mutation of the K-ras gene in sporadic colorectal cancer. The alimentary "environment" of the Neapolitan court of the XV century, with its abundance of natural alimentary alkylating agents, well explains this acquired mutation. These and other diseases as, for example, a fatal puerperal complication, a thyroid goiter, a case of Wilson's cirrhosis, some cases of anthracosis and other peculiar traumatic conditions, such as a mortal stab-wound, can elucidate the pathocenosis of the wealthy classes of the Italian Renaissance.