Among 133 chemical laundries workers and 107 persons from a control group internal medical examinations together with electrocardiography record and laboratory investigation were performed. For the assessment of liver functions designations AlAT, AspAT, FA, prothrombin index, bilirubin and iron content in serum, proteinogram and thymol turbility test were prepared and carried out. No statistically remarkable differences between the group of women exposed to PER and the control group were found. In the study group of males statistically noticeable differences were related to mean values and the number of deviations connected with aminotransferases. An increased activity of these enzymes was observed in persons exposed to high instantaneous concentrations of PER. The author reflects upon the usefulness of performing biochemical investigation of the liver function during prophylactic examination of laundry workers exposed to PER.