The presence and distribution of macrophages, several subtypes of lymphocytes and HLA antigens in the human testis were studied using monoclonal antibodies and immunocytochemical staining. Cells identified as tissue macrophages were relatively abundant. They were dispersed individually in the interstitium and were often included in Leydig cell clusters. Occasional macrophages were observed in the tubular wall, but never in the seminiferous tubules. Very few lymphocytes were found in the testicular interstitium. These were mainly T lymphocytes. T helper/inducer and T cytotoxic/suppressor cells were extremely scarce. B1+ cells were not observed, but occasional Leu‐14+ cells could be seen. NK cells were not found. The number of T lymphocytes in the tunica albuginea was considerably higher than in the interstitial tissue. HLA‐ABC and HLA‐DR antigens could be observed in the endothelial cells and macrophages which were both strongly positive. The myoid cells and the Leydig cells expressed these antigens only weakly. Neither of the HLA antigens was expressed in the germinal epith