Goeckerman regimen (GR) of psoriasis includes daily dermal application of crude coal tar (CCT) and dermal exposure to UV-A and UV-B radiation. Observed group consisted of 23 patients with psoriasis treated by GR. Therapeutic ointment contained 5% of CCT. The level of psoriasis area and severity index was significantly decreased after GR (P < 0.001) and confirms high efficiency of GR. High levels of selected metabolites of pyrene and phenanthrene indicated high level of dermal penetration. We found significantly increased urinary mutagenicity in samples collected in the middle and in the end of GR (TA98+S9, P < 0.01; YG1041-S9, P < 0.001; YG1041+S9, P < 0.001). Significant increasing of chromosomal aberrations in peripheral lymphocytes (CA) in blood samples collected in the end of GR (P < 0.001) and consecutive decreasing of CA in 78th day after the end of GR has been observed. Almost all results indicated that the patients could be endangered by a peak genotoxic exposure. Nevertheless, the genotoxic effect does not seem to be long lasting. Despite conflicting results from cancer epidemiological studies, it is evident that single GR can contribute to the total load of environmental mutagens in a group of treated patients.