The cytological features of the pituitary of normal male inbred Swiss albino mice were studied. On the basis of 4 staining methods (CW, MTS, PAS-OG-MB, AT-PAS-OG), 5 types of chromophil cells have been identified: 2 types of acidophils--red and orange--and 3 types of basophils--angular to polyhedral dark-staining large cells, dark-staining small round cells and oval light-staining large cells.