The aim of the present study was to demonstrate the immunocytochemical localization of ferritin in human Leydig cells. Testes from patients orchidectomized for carcinoma of the prostate were used. The immunoreactivity for ferritin was visualized in the Leydig cells by amplification immunocytochemical technique. The Sertoli cells and some of the germ cells show moderate immunoreactivity for the examined antigen. Our result represent an immunocytochemical verification for presence of ferritin in the human Leydig cells (also in other cellular components) and suggest the role of this factor in the local auto- and/or paracrine control of the testicular functions.