The aim of this study was to investigate the histologic charasterictics of anterior pituitary cell types Irt the im· mature and mature males and also in immature, mature, pregnant and lactating female rats with the light microscope. As a material. 30 pituitary glands provided from Wistar albino rals were used (20 lemales and 10 males). Acidophilic cells were lound to distribute throughout the pars distalis In all groups. These cells were round or ovoid in shape, and their nuclei were also round and localized eccentrically and the cells in contact with sinusoids. Their numbers were more greater al both lac· tational and pregnancy than these of the other stages. Although the tireotropic cells distributed throughout the pars distalis, these cells were observed more diffuse in the centrial and lateral areas 01 pars distalis. These cells were round, ovoid, stellar and various in shape. and their nuclei were large and round in shape. Their numbers were the greatest in mature female and they were much more in female than male. The round-ovoid shaped gonadotrophic cells were observed throughout the pars distalis. Their nuclei were round in shape. These cells were found at maximum numbers. depending on the se· xual period in the mature female.