Departments of Venereology, Clinical Pathology, and Obstetrics and Gynaecology, Al Hussein Hospital, Al Azhar University, Cairo, Egypt High titres of antisperm antibodies have been found in the sera of patients suffering from obstruction in the sperm passages (Shulman, 1971; Abdel Aal, El Atribi, Abdel Hafiz & Aidaros, 1975). The presence of antibodies in the interstitial spaces and in damaged basement membranes in the testicular tissue of infertile men was reported by Isidori, Dondero & Garufi (1968) and Isidori, Dondero & Lombardo (1970), who used an immunofluorescence technique, and confirmed by Le Lorier, Salat & Rotman (1970). The incidence of immunological lesions in the testes of infertile men was about 22·3% (Le Lorier et al., 1970; Isidori et al., 1973). In normal men, testicular immunoglobulins mainly occur in the interstitial cells and their concentration in the germinal cells is very low (Abdel Aal, Abdel Hafiz, Kandil & El Tonsy, 1976). The