Overexpression of p53 protein has been reported to correlate with a poor prognosis in endometrial cancer. Most endometrial adenocarcinomas are clinical stage I at the time of diagnosis and the majority of women to die of this neoplasm had stage I disease at initial presentation. The aim of our study was to evaluate the prognostic significance of p53 overexpression in early stage endometrial carcinoma. Ninety-two patients with surgically treated endometrial adenocarcinoma FIGO stage I were examined for overexpression of immunohistochemically detected mutant p53 protein. Follow-up time ranged from 0.4 to 137.8 months (mean, 34.8). Thirteen women died of their tumor. A nuclear staining reaction for p53 was observed in eight cases. Women with p53 protein overexpression showed a significant poorer overall survival in univariate analysis (relative risk, 4.78; 95% confidence interval, 1.56-14.61; P = 0.006, Wald test) and also in multiple analysis adjusted for grading (relative risk, 4.39; 95% confidence interval, 1.39-13.90; P = 0.01, Wald test). Histological grading and histologic stage did not correlate with p53 protein overexpression (P = 0.26, P = 1.0, respectively, exact chi 2 test). Immunohistochemically detected p53 protein overexpression in early stage endometrial adenocarcinoma could aid in predicting prognosis and subsequently have some impact on adjuvant therapy.