The mutation of the p53 gene is a common phenomenon in numerous human tumors including breast cancer. It leads to an accumulation of nonfunctioning p53 protein in the cell nuclei, which can be detected by immunohistochemical techniques. In breast cancer overexpression of mutated p53 protein has been correlated to a poor prognosis. Our study is an immunohistochemical analysis of p53 in 82 cases of breast cancer in young (< or = 30 years old) Kuwaiti women, correlating it with histopathological grade, lymph node status, estrogen (ER) and progesterone receptor (PgR) content, tumor cell proliferation (immunostaining for Ki-67) and expression of c-erbB-2 oncoprotein. p53 immunostaining was found in 47 (57.32%) of the carcinomas. 65% of them displayed positive immunostaining for c-erbB-2. 63.7% of tumors with p53 overexpression were aneuploid. 64.8% of the p53 positive tumors were node positive. 93.5% of the p53 immunopositive carcinomas were ER-negative, and in 95.7% of this subclass of patients no PgR could be detected. The vast majority of p53 positive carcinomas were grade III (76.6%), 21.3% were grade II and 2.1% grade I, but neither tumor grade or tumor size showed a correlation with p53 expression. A significant negative correlation between ER- and PgR-content (p = 0.006) and immunostaining for p53 was observed. Our study provided evidence that the association of negative hormone receptor status and positivity for p53 immunostaining points to a greater tumor aggressiveness.