The present study investigates Italian Paracelsianism and chemical medicine from the mid-16th century to the early 17th century. In Italian states, Paracelsus and his followers were initially seen as proponents of new chemically prepared medicines. Head-on attacks on Galenic medicine were rather isolated. Paracelsian medical theories were adopted by many physicians, who tried to establish a compromise with traditional medicine. As attested by Pietro Castelli, the attitude to compromise did not prevent Italian physicians from introducing changes in medicine, notably in physiology. Castelli pursued new approaches to medicine giving chemistry a central role to physiology and therapeutics. From the Accademia dei Lincei to Borelli’s early medical works, theories and practices proposed by the Paracelsians played a central part in Italian science and medicine.