Eight cases of early adenocarcinoma selected from 101 adenocarcinomas of the uterine cervix were studied to establish the criteria of early adenocarcinoma. Lesions of these 8 cases were small in size. In 7 of 8 cases, these tumors originated in the area of the squamocolumnar junction (SCJ). Tumor cells consisted of two types of atypical columnar cells, i.e., tall columnar cells with enlarged and deeply eosinophilic cytoplasm and clear cells with enlarged and clear vacuoles. Tall columnar cells showed weak or negative reaction to high iron diamine (HID) stain and negative to Alcian blue (AB) stain. Clear cells showed negative reaction to HID stain and positive to AB stain. Although normal endocervical columnar cells showed markedly positive reaction to HID stain and negative reaction to AB stain, invasive adenocarcinoma cells showed similar reaction to early adenocarcinoma cells. From this study, it is surmised that early adenocarcinoma of the uterine cervix originates in the area of the SCJ and consists of tall cells in all cases and clear cells in 4 of 8 cases, and that HID-AB stain is useful in differentiating early adenocarcinoma cells from normal endocervical columnar cells.