Background: Hereditary cancer syndrome about ovary cancer is mostly BRCA related. But mismatch repair genes related Lynch syndrome is also associated with it.There is not much study about risk evaluation about this among Korean population. We investigate this. Methods: A retrospective review of ovary cancer patients who was counseled about Lynch syndrome in Department of Obstetrics and gynecology, Samsung Changwon Hospital by single surgeon was done. Clinical information was extracted from the medical record including age, family and personal history of cancer, immunohistochemistry (IHC) of MLH1/MSH2, microsatellite instability test (MSI). Results: Total test was 26.mean age was 54(16~75) and fifty percent was serous type (13/26).There were 2 patients with Lynch syndrome related cancer family history (stomach and ovary) among their 1^st degree relatives. Only one patient has abnormal MLH1 IHC.There were three unstable MSI patients (BAT26, D2S123, D55346, and NR21). Conclusions: We found three abnormal MSI patients among this population. Cost effective algorithm using multiple genetic testing to find Lynch syndrome associated ovary cancer patients should be developed through large population study.