Early reports of male immunological infertility suggested a decline in antisperm antibody concentrations in some patients after even short-term (10 day) therapy with low-dose prednisolone. In the present study, 53 men with positive results in spermatozoal mixed antiglobulin reaction (MAR) and serum tray agglutination tests (TAT), were randomized to receive either 20 mg of prednisolone or placebo daily for 2 weeks prior to in-vitro fertilization (IVF) treatment. The antibody levels were also monitored by flow cytometry (FCM). There were no significant differences between these groups as regards fertilization rates (35% with prednisolone; 39% with placebo) and pregnancy rates (29%; 32%). No significant changes occurred in either MAR or FCM results in relation to therapy. Patients with fertilization rates of < 10% had significantly higher immunoglobulin G (IgG) MAR values compared with those with better fertilization, whereas there was no relationship between IgA levels and fertilization results. As regards FCM, the results were similar, but without statistical significance. In conclusion, IVF is a good course of action in severe male immune infertility, but low-dose prednisolone therapy does not lower the sperm-bound antibody numbers and does not improve the IVF outcome.