Motility and other characteristics of human sperm can be measured by computer-assisted sperm analysis of samples stained with Hoechst 33342**Supported in part by a subcontract SBIR 2R44 ES0562 to Cornell University, Ithaca, New York, from The Small Business Innovative Research Program, National Institutes of Health, Bethesda, Maryland.††Hoechst 33342, Sigma Chemical Company, St. Louis, Missouri.