One hundred seventy-eight couples with positive antisperm antibody titers in serum and genital secretions were offered treatment with prednisone. Of 60 couples who received prednisone only, 43% conceived. Of 25 who had no therapy, 48% conceived. Fifty-four patients treated with prednisone received additional therapy and 31% conceived. Ten of 39 patients not treated with prednisone but receiving other therapies conceived. Cytotoxic antibodies were reduced in 30% to 42% of serum samples and in 24% to 33% of genital secretion samples. In those couples with decreased cytotoxic antibodies pregnancy rates were 40% to 60% compared with 0% to 23% in those with decreased hemagglutinating antibody titers. Our data suggest that prednisone did not improve overall pregnancy rates; pregnancy rates were comparable in both groups treated with other therapies; donor insemination was the most successful of the alternative therapies; reduction of cytotoxic antibody titers after prednisone treatment was associated with increased pregnancy rates.