HLA‐A and ‐B antigens have been found in purified spermatozoa using a double fluorescence cytotoxicity tecnique and specific absorptions. HLA‐C, ‐Bw4, Bw6 and ‐DR antigens have not been found using the same techniques. Controversial results regarding HLA expression on spermatozoa have been presumably obtained because of a lack of both seminal cell purification and an appropriate more accurate cytotixicity technique. The presence of HLA antigens on seminal cells may be of relevance to explain the postulated immunosuppressive alloimmunization which may occur in the acquired immunodeficiency syndro