The distribution of laminin and collagen type IV in the basement membrane of 45 uterine cervical adenocarcinomas was studied using immunohistochemical techniques. Staining patterns of basement membranes were divided into three types, according to the intensity of staining: thick and discontinuous (type I), thin and discontinuous (type II), and fragmentary (type III). In well-differentiated adenocarcinomas, 17 of 24 cases (71%) showed type I and the remaining 7 showed type II. In contrast, in poorly differentiated adenocarcinomas 4 of 5 cases (80%) showed type III. Five of six cases (83%) of adenoma malignum, even though extremely well differentiated, showed type III. Staining patterns of the basement membranes correlated with histological grade. Five-year survival rate of patients with type I and II staining (74%) was better than that of patients with type III (55%).