At the end of the year 1983 and at the beginning of 1984, groundwater contamination with tetrachloroethylene was discovered south of Graz. Many wells showed an elevated concentration of tetrachloroethylene. 1210 persons living in this area were examined. As tetrachloroethylene may cause liver damage, screening tests were carried out in order to detect pathological liver function tests (LFT), such as gamma-GT elevation. In most cases, initially elevated LFT could be attributed to alcohol abuse. After thorough medical examinations, two cases remained unclear; later on, however, the initially elevated LFT could no longer be detected. This is a certain indication that there was some type of stress on the liver shortly before the blood sample was taken. In all other cases of liver disease, the causes could be determined. The pollution of drinking water was not the cause of pathological LFT. Nevertheless, the inhabitants of this region will receive drinking water from the public water supply for safety reasons. However, one thing that needs to be stated very clearly is that these findings which fortunately show no detrimental effect due to the pollution of drinking water, do not allow any conclusions concerning the possibility of injury to health, i.e. they do not preclude possible impairment of health as a consequence of prolonged consumption of the polluted drinking water.