A commercially available enzyme-linked immunosorbent assay (ELISA) kit for the detection of antisperm antibodies in serum was compared with standard sperm immobilization test (SIT) with the use of sera from 83 infertile women and 29 control individuals. For the ELISA, 24% of the infertile patients and 10% of the controls showed positive results, whereas 15% of the patients and none of the control were positive in the SIT. Parallel tests carried out on the same sera indicated that these methods detect a different, though often overlapping, spectrum of antibody activity. The presence and number of motile sperm in cervical mucus during postcoital tests were found to be related to the results of the SIT. On the other hand, the ELISA did not appear to be related to the quality of postcoital tests. These data indicate that care must be employed to interpret the results of this ELISA kit for the detection of antisperm antibodies.