ABSTRACT: A simple and reliable enzyme-linked immunosorbent assay (ELISA) for the detection of antisperm antibodies has been developed in our laboratory. The antigen for the solid phase was produced by sperm sonication while antihuman globulin conjugated to alkaline phosphatase was used as the developing reagent. The conditions and reagents of the assay were chosen to give a mild treatment of the antigen, simple manipulation during washing steps, and nontoxic and readily available reagents. The results were compared to a conventional microscopical method routinely used in our laboratory that detects agglutinating antibodies to human spermatozoa. In 96% of all cases antibodies detected by the microscopical method were also detected by ELISA. Moreover there were some cases where no antisperm antibodies could be demonstrated by microscopy, but gave a positive reaction with ELISA. These were usually cases of unexplained oligospermia, agglutinates in the ejaculate, and bad motility or low viability of the sperms. These results, and also titration experiments of positive samples demonstrate the higher sensitivity of the ELISA by comparison with microscopical methods.