The objective of this study was to evaluate the role of p53 immunoreactivity as a prognostic marker in prostate cancer.The nuclear accumulation of the aberrant p53 protein was determined by immunohisto-chemistry on surgical specimens and related to stage, grade and cancer-specific survival in 186 prostate cancer patients treated with transurethral resection and subsequent surveillance.There was a significant correlation between p53 staining and grade: 2% of the highly differentiated, 8% of intermediately, and 21% of the poorly differentiated tumors stained. Patients with p53-positive tumors had a significantly shorter survival (52 months) than the p53-negative group (123 months). However, in a Cox multiple regression analysis of p53 status, tumor stage, grade, metastasis and age, p53 lost its significance as an independent predictor.p53 is a rare and late event in prostate cancer, indicating that other molecular mechanisms may be of greater importance in the development of prostate cancer. The predictive value of p53 apparently depends on its association with high grade and advanced stage, and it is not a useful prognostic marker in prostate cancer. However, p53 status could play a role in the evaluation of patients prior to radiotherapy since p53 inactivation may produce radioresistant tumors.