Estrogen receptors (ER) in human gallbladders were examined immunohistochemically using a specific monoclonal antibody against human ER. ER immunoreactivity was positive in 6 (19.4%) of 31cases of cholelithiasis, 6 (33.3%) of 18 cases of epithelial polyp, 14 (53.8%) of 26 cases of adenoma, and 26 (22.8%) of 114 cases of adeno‐carcinoma. ER immunoreactivity was located at the nucleus of the epithelium of both non neoplastic and neo‐plastic tissues, although the number of ER‐immunoreactive cells was small. There was no sex difference in the incidence of ER immunoreactivity. No significant difference in survival rates could be demonstrated between ER‐positive and ER‐negative carcinomas. Epithelial polyps, adenomas and carcinomas were divided into metaplastic type and non‐metaplastic type based on the presence or absence of metaplastic changes for comparison of the incidence of ER immunoreactivity. The incidence of ER immunoreactivity in the metaplastic type was significantly higher than that in the non‐metaplastic type. We conclude that ER are present in the gallbladder mucosa in various disease states and suggest that the presence of ER is related to metaplasia of the gallbladder mucosa. Acta Pathol Jpn40