Ovarian cancer is a highly lethal disease and its underlying biology is poorly understood. The p63 is a homologue gene of the tumor suppressor p53. p63 appears to be important for the development and differentiation of reproductive epithelium and interacts with p53 in human tumorigenesis. This study presents the immunoexpression of the p63 in benign and malignant epithelial ovarian tumors. We evaluated the p63 immunoexpression in 91 ovarian benign cystadenomas (29 mucinous and 62 serous) and in 29 ovarian malignant tumors (3 mucinous borderline, 3 serous borderline, 17 serous carcinomas, 2 endometrioid, 2 undifferentiated, 1 mucinous, and 1 clear-cell carcinoma) using a monoclonal antibody clone 4A4 (1:200), which recognizes all p63 variants. The tumors were considered p63 positive if 5% or more cells presented nuclear immunostaining. We observed 85.7% of positivity in benign tumors, 50% in borderline tumors, and 8.7% in invasive ovarian cancer (P < .0001). The benign serous cystadenomas were positive in 91.9% of cases and benign mucinous cystadenomas in 72.4% (P= .02). These data suggests an important role of p63 in the control of ovarian epithelium behavior. The p63 may be involved in the development of benign and malignant epithelial ovarian tumors.