Cancer is a common term for a number of diseases whose main feature is that they occur as a result of changes in the DNA and professional cancer is cancer that has emerged as a result of exposure to carcinogens in the working environment. Occupational cancer has no differences either clinically or biologically of cancer of any other origin. Today it is considered that exposure to carcinogens in the workplace cause 4-10 % of all cancers in men and about 4 % of cancers in women. Workplace carcinogens are divided according to the carcinogenic potential to cause malignant transformation and that division is made in the IRAC and the European Union. Carcinogens are divided in three major groups - physical, chemical and biological carcinogens. Today it is known that 56 occupational hazards certainly causes cancer, 40 of them most likely causes cancer and 113 occupational hazards were classified as possible carcinogens. The most common occupational cancers are those of the respiratory tract, organs of mesothelial origin, bladder and skin. Considering that in Croatia every fourth man dies of cancer and a substantial percentage of cancer is caused by carcinogens in the workplace, prevention of the exposure to the carcinogens and regular health check-ups are very important factor in reducing the incidence of cancer. Republic of Croatia with the legislation and regulations has regulated the obligations of employers and of workers' rights that reduce the exposure to the carcinogens at work in a way that it does not affect the health of workers and allow regular medical examinations for all workers who are in contact with occupational hazards.