Blocks of tissue and mucosal scrapings from normal, pathological, pregnant, and menopausal human uteri (a total of 57 specimens) were fixed chiefly in basic lead acetate, some in Susa, and some in formalin. Paraffin sections were stained by 0.5% watery toluidin blue, hematoxylin-eosin, and Domi- nici. In all groups except the postmenopausal uteri, there were certain cells characterized by occasional metachromatic granules. They were neither mast cells nor, apparently, plasma-mast cells. During the proliferation stage there was found in the mucosa a metachromatically staining substance which is not met in the actual secretory stage.