Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous compounds in our environment. They are formed during incomplete burning of coal, oil, gas, wood, garbage or other organic substances such as tobacco and charbroiled meat. PAHs enter the environment mostly as releases to air from volcanoes, forest fires, residential wood and coal burning and exhaust from automobiles and trucks. There are more than 100 different PAHs. Some of them have danger toxic properties including mutagenic and carcinogenic potential. Since 1993 PAHs are classified as the compounds which can cause immunosuppression. They reduce the body resistance against infection and cancer diseases. Immunosuppressive, carcinogenic and hypersensitivity effects of some PAHs representatives were described well in experimental studies. On the other hand, only sporadic information about immunological changes after long-term occupational exposure to PAHs were found from existing human epidemiological database. In addition, these studies usually did not cover the complex immunological profile represented by cellular and humoral activity.