Biological monitoring of occupational exposure to toxic compounds enables an early detection of adverse health effects. Apart from the standard biological monitoring methods of occupational exposure represented by metabolites and enzymes activities analysis also immunological detection methods seem to be promising. The changes of immunological system are demonstrable extraordinary sensitive markers of load of organism. The process of welding belongs between important sources of pollution of working environment with heavy metals and other harmful compounds including polycyclic aromatic hydrocarbons. According to IARC classification the welding fumes are included into group 2B and are supposed as possible human carcinogens. Numbers of different epidemiological studies have proved relationship between welding and serious health disorders namely malignancies. We recorded a number of changes in immunological parameters when compared with those in control group in our study. The results of analysis were statistically evaluated. The statistically significant reduction of number of phagocytosis capable cells was found in the group of welders when compared with the control group. The levels of neopterin, beta-2-microglobulin and IL-1 beta have indirectly monitored cell component of immunological response. In the case of these markers a statistically significant increases were found in the group of welders. We found statistically significant IgM decrease and statistically significant IgA increase in humoral responses with the same group when compared with control group.