The aim of this study was to evaluate the presence and distribution of p53 alterations in pure endometrioid adenocarcinomas (n = 120) of different grades and stages, as opposed to normal endometrium (n = 13) and various risk groups of hyperplasia (n = 39). All samples were initially analysed by immunohistochemistry with the monoclonal antibody Ab-6. Normal endometria were negative. With increasing degrees of malignancy, the number of cases with p53 accumulation rose and ranged from 9% to 18% in hyperplasia, through 25% in low-grade carcinomas (G1), to 69% in high-grade carcinomas (G3). This increase was also seen when comparing tumours by stage. Of carcinomas in stage IA, only 17% showed p53 immunostaining, in contrast with 72% in stage IC. Of this material, 34 carcinomas and 8 hyperplasias were analysed for p53 mutations in exons 5-8 by means of polymerase chain reaction and temperature-gradient gel electrophoresis (TGGE). In none of 5 hyperplasia and 6 of 12 carcinomas showing p53 accumulation by immunohistochemistry, p53 mutations were detected by TGGE. In contrast, 4 of 22 carcinomas harboured mutant p53 but were negative by immunohistochemistry. Immunohistochemical and molecular investigations revealed that p53 alterations are related to the standard prognostic markers of endometrial cancer, i.e. grading and staging. TGGE, an indirect screening procedure for p53 mutations, is used to detect the type of p53 alteration and may provide additional insight into the complex figure of p53 abnormalities in the development and progression of malignant endometrial lesions.