The reproductive effects of carbon-disulfide (75150) (CS2) were investigated in rats. Male Long-Evans-hooded-rats were used in two experimental protocols. The first group was exposed to 0, 350, or 600 parts per million (ppm) CS2 for 10 weeks prior to sacrifice. Reproductive organ weights, epididymal sperm count, and hormone activities (luteinizing, follicle stimulating, and testosterone) were measured. In protocol 2, after exposure to 600ppm CS2, each animal was mated weekly and coital behavior, ejaculated sperm count, and hormone content were monitored after 0, 1, 4, 7, and 10 weeks of exposure. Epididymal sperm counts were similar in all groups, but were slightly lower in the 600ppm CS2 group. Plasma testosterone content was significantly lower in animals exposed to 600ppm CS2. Mount latencies were significantly reduced after 7 weeks of exposure, while ejaculation latencies were significantly decreased by week 4 of CS2 exposure. A marked decrease in sperm count occurred after 7 weeks of CS2 exposure and remained depressed throughout the 10 weeks of exposure. There were no significant treatment related effects seen in plasma follicle stimulating or luteinizing hormone values. Histologic examination of the testes of animals exposed to 350 or 600ppm CS2 showed no alterations from normal. The authors conclude that CS2 is a toxin of the male reproductive system resulting in abnormal coital behavior and decreased sperm counts.