Epithelial ovarian cancer is the second most prevalent type of gynecological cancer. We aimed to investigate prognostic factors related to survival in patient with 2014 FIGO stage IIIC high-grade serous ovarian cancer (HGSOC). Two hundred fifty eight patients were evaluated retrospectively. The absence of a visible tumor was determined as maximum cytoreduction, and a residual tumor size of 1 cm or less was determined as optimal cytoreduction. Patients who underwent cytoreduction followed by a combination of platinum and taxane adjuvant chemotherapy were included. Exclusion criteria for the study were patients taking neoadjuvant chemotherapy and those with suboptimal surgery. Optimal cytoreduction was performed in 107 and maximal cytoreduction was performed in 151 patients. The five-year PFS rate was 27% and the five-year DSS rate was 76%. While high ascites volume and optimal cytoreduction were identified as independent prognostic factors for disease failure, only optimal cytoreduction was an independent prognostic factor for survival. The maximal cytoreduction is improves PFS and DSS in patients with 2014 FIGO stage IIIC HGSOC as our study results. Therefore, maximum surgical effort and radical cytoreductive procedures should be performed.