The effect of long‐term occupational exposure to CS2on various endocrinologic parameters was studied in 15 exposed men and 16 age‐matched controls. Duration of exposure varied between 10 and 36 yr. The CS2concentrations in the viscose rayon plant have been below the Finnish threshold limit value of 30 mg/m3(10 ppm) under normal operating conditions for the past 10 yr. Before this the exposure was considerably greater. Of the various endocrinologic parameters, serum follicle stimulating hormone (FSH) and luteinizing hormone (LH) were significantly increased in the exposed group, seven workers having values above the reference limit. This was taken as a sign of primary gonadal insufficiency, which was considered only latent as serum testosterone values were unaffected. No changes were seen in serum prolactin values before or after stimulation with thyrotropin releasing hormone (TRH). No disturbance was seen in thyroid function as evaluated by serum thyroxine (T4), free thyroxine index (FTI), triiodothyronine (T3), and the thyrotropin response to TRH. Serum cortisol was also unchanged. These results may reflect high exposure during past decades rather than exposure to the present low CS2concentrations.