Department of Anatomy, Laboratories of Tissue Culture and Electron Microscopy, University of Padua, Italy (Received 12 March 1974) Attempts to grow adult mammalian adrenocortical cells in vitro are justified by the fact that most of the work reported until now (Kahri, 1966; Milner & Villee, 1970) refers to cultured foetal or newborn rat and human adrenal glands and, furthermore, by the knowledge that the zonation and the metabolic features of adrenocortical cells at these early stages of life differ from those possessed by adult cells (Bloch, 1968). We recently reported a method for tissue culture of the adrenal cortex of adult rats (Armato & Nussdorfer, 1972). In this communication, we describe the successful cultivation of adult human adrenocortical cells. Wedge biopsies of normal human adrenals were obtained from adult patients undergoing urological operations, put into cold (4 °C) Eagle's MEM (Wellcome, London) and were brought to the laboratory. About 20