Background: Ovarian cancer comprises a heterogeneous group of neoplasms. The prognosis cannot be predicted by histopathologic examination alone. The aim of this study is to evaluate p53, PTEN, and β-catenin expressions in primary ovarian carcinomas in an attempt to find a possible relationship with morphologic parameters and clinical findings.Methods: The study included 100 epithelial ovarian tumors (borderline and carcinomas) from affiliated hospitals of Shiraz university of medical sciences during 2007-2013. Immunohistochemical staining for p53, PTEN, and β-catenin was performed on 65 serous, 18 mucinous, 10 endometrioid, 5 clear cell, and 2 mixed tumors.Results: p53 expression pattern in serous carcinoma significantly differed from endometrioid carcinomas. Strong positivity (2+) in >50% of the tumor cells favored serous carcinoma. PTEN expression significantly differed in mucinous and serous carcinomas as well as in endometrioid carcinoma and borderline endometrioid tumor. There was significantly decreased β-catenin expression in the carcinomas compared with borderline tumors. In all of the different subtypes of ovarian carcinomas, we observed a significant association with decreased β-catenin expression to tumor grade as well as in serous carcinomas with increased nuclear grade, mitosis, and tumor grade. There was no significant relation between expressions of p53, PTEN, and β-catenin in epithelial ovarian tumors to FIGO staging, response to chemotherapy, serum CA- 125 marker, and tumor recurrence.Conclusion: p53 and PTEN are helpful in differentiation of some epithelial ovarian tumor subtypes. In serous carcinomas, diminished expression of β-catenin is associated with higher tumor and nuclear grade. This expression is significantly different in borderline and carcinomas.