To determine the concentration of polychlorinated biphenyls (PCB), hexachlorobenzene (HCB) and gamma hexachlorocyclohexane (gamma HCH) in human seminal plasma, 176 ejaculates taken from 156 patients consulting the Dept. of Gynecology and Obstetrics of the RWTH Aachen for sterility were analysed gas-chromatographically. 77% of the examined samples exhibited different pathological sperm findings (OAT, AT, OA, A, O, T, P, K). Contrary to all our expectations the concentration of PCB, HCB and gamma HCH in the samples with normozoospermia were higher than in the samples with pathological sperm findings. The wives of 42.5% of the patients with normozoospermia exhibited no organically or endocrinologically reasons for sterility (idiopathic sterility). In this group (normal/idiopathic) the concentrations of the toxic agents were significant higher than in that group of patients with pathological sperm findings. In the group of couples with male normozoospermia and female organic/endocrinologic reasons for sterility (normal/organic) nearly the same concentrations of PCB, HCB and gamma HCH could be shown as in samples with pathological sperm findings. The concentrations of the toxic agents in the samples with the different pathological sperm findings were similar--independent of the kind of diagnosis. A correlation between the spermiogram parameters motility, morphology and density and the concentration of PCB, HCB and gamma HCH in the seminal plasma could not be shown.