The goal of this study was to confirm the capacity of occupational medicine to become involved in cooperative screening programs with a dosage of the PSA (Prostate Specific Antigen) determined by immunoradiometric assay. Two thousands and five hundred seventy three salaried workers in the building sector, between 50 and 65 years old, participated in this investigation. Thirty seven individual ie 1.4% had a PSA level above or equal to 10 micrograms/l. Among them, 35 were checked within three months and 17 were found to have a persistently elevated PSA level. In this subgroup 15 pathologies including two cancers were found. We observed a great variability in the results of PSA determination in the groups of individuals whose initial assay level was above or equal to 10 micrograms/l. The linear correlation coefficient between the two assays (on the same individual), carried out at a six week interval on average, was low (r = 0.52 for N = 35). In our series, 3.5% of patients followed up had undergone a rectal examination less than a year previously. Occupational medicine seems to be an efficient setting for screening intervention. However, the people mainly concerned by our study, (salaried workers seen through the physicians interviewed) did not seem very aware of this type of action.