Expression of the HER-2/neu proto-oncogene product was looked for immunohistochemically in 222 endometrial carcinomas in a retrospective follow-up study. The intensity of protein expression was correlated with patient survival. Median follow-up time was 4.8 years. In 109 (49%) of 222 endometrial carcinomas there was aberrant expression of HER-2/neu. HER-2/neu-expression did not correlate with p53-expression and proliferation rate, as determined immunohistochemically by the monoclonal antibody Ki-S1. In univariate statistical analysis aberrant HER-2/neu expression was not predictive of adjusted survival (p = 0.18) and of disease-free survival (p = 0.42). In multivariate analysis HER-2/neu-expression was not found to be an independent prognosticator (p = 0.099) as compared to FIGO-stage (p = 0.0001), histologic grade (p = 0.00099) and proliferation rate (p = 0.0013). Therefore immunohistochemically detected expression of HER-2/neu seems not to be a clinical prognosticator in endometrial cancer.