Objective: Assessing role of morphology and immunohistochemistry in distinction between primary and metastatic ovarian endometrioid carcinoma. Subjects: 19 patients who have been diagnosed and undergone surgery for simultaneous endometroid ovarian and uterine carcinomas in the National OBGYN Hospital from January 2000 to December 2012. Methods: descriptive retrospective. Study variables are age, morphology and rate of occurence, degree of ER, PR, CK7 expression. Results: Average age of the patients was 45 + or = 3.7 years. The age groups of 60 and 41 - 50 were more common (42.1 percent and 36.8 percent respectively), while the age group of or 60 were less (10.5 percent each group). There were 52.6 percent of the cases diagnosed as simultaneous endometroid ovarian and uterine carcinoma. The results also have shown that 100 percent of the cases were diagnosed as ovarian tumor, while only 10 out of 19 cases were diagnosed as endometroid carcinoma via endometrial biopsy. There were 17 out of 19 cases confirmed as unilateral tumor, and there were 15 out of 19 cases with the tumor diameter measured less than 10 cm. No case with broken tumor capsule or polyp observed. Commonly, tumor tissue had expanded to the whole uterine cavity (7/19 cases). All of the ovarian and uterine specimens were CK7 positive, an exclusive criterion for gastrointestinal metastasis. Expression degree of endocrine markers was less in ovarian tumors than in uterine tumors. Conclusion: There is a significant of morphology and degree of ER, PR expression in the distinction between primary and metastatic ovarian endometrioid carcinoma.