The Occupational Doctor plays a key role on the protection of workers safety and prevention of occupational and work-related disease. His training and his need of updating, due to the constant transformation of work, the evolution of technology and the medical progress, set him in the center of all activities carried out to protect health in workplaces. The Occupational Doctor should devote special attention to the working anamnesis as well as to the pathological anamnesis both close and remote. He should also pay attention to semeiotics. Another important element is the relationship between the Occupational Doctor and the Doctor of General Medicine (MMG); this synergy is of vital importance in protecting health and in investigating diseases whether occupational or not. D.Lgs. 81/08 emphasizes this synergy, in fact name and phone number of Doctor of General Medicine is compulsory in Case History. Major source of information for all form of prevention is the survey of occupational disease which is a tool for epidemiological control. The use of a systematic collection of data, of protocols, of guidelines and of scientific evidence is the basis for identifying occupational diseases, their diagnosis and subsequent denunciations. This is the line suggested in MAL PROF informative system, made for registration of work-related diseases, and which is important, with other instruments, in realizing an integrated informative system for prevention in workplace. The Covenant for the Protection of Health and Prevention in Workplaces (DPCM 17/12/2007) indicates the strategic objectives of the National Health System for the consolidation and development of the existing system and of the programs promoting health and safety. These include the growth of the culture of prevention and of the epidemiological control of occupational diseases. The Occupational Doctor has an important role because he can identify the early onset of diseases during the working age and start all forms of prevention and health promotion. In the case of diagnosis of a suspected professional disease the Occupational Doctor has three distinct obligations. The first is to report to the legal authority (C.P.P. art. 365). The second requirement is the declaration of the occupational disease (D.P.R. 1124/65 art. 139) and the third is to issue the first certificate of occupational disease for compensation insurance (D.P.R. 1124/65 artt. 53, 251).