Bernardino Ramazzini is the recognized father of occupational medicine. His work De morbis artificum diatriba, printed in Modena in 1700, is the first comprehensive treatise on the diseases of workers. Ramazzini was the first physician to investigate systematically the relationship between work and disease. The method applied, including an accurate medical examination, an inspection to workplaces to observe workers' activities, and a collection of existing knowledge, is surprisingly up-to-date. But the most modern part of his method was the acknowledgement of the role of prevention: Ramazzini identified several precautions to limit exposure to hazards, and also recognized the fundamental role of informing and training the workers about the occupational risks and how to protect themselves. As a conclusion, the contribution of Bernardino Ramazzini to occupational medicine is not limited to the recognition of a large number of occupational diseases, but is also, and mainly, in the method developed.