The paper deals with the concepts of environmental monitoring and health surveillance, which include the following tasks: biological monitoring, health information, pre-employment and periodical medical examinations. Biological monitoring permits evaluation of the degree of exposure and its early effects. The early effects can be detected with specific tests exploring initial biological alterations while the organism is still capable of compensating such changes. Application of biological monitoring requires a profound knowledge of toxicology and health surveillance in general terms requires a solid basis of occupational medicine in order to set objectives and make judgements concerning fitness for specific jobs. Details are given of the measures the occupational health physician must take and when he must take them in the case of development of an occupational disease. Particular attention is given to the removal of the subject from exposure, the first certificate of occupational disease, the notification to the Local Health Unit and the diagnosis.