Aim: The aim of this study was to analyze the survival outcomes of stage IIIC ovarian high‐grade serous carcinoma (HGSC) patients with both peritoneal and lymphatic dissemination (IP+/RP+) who had undergone maximal or optimal cytoreduction followed by intravenous carboplatin/paclitaxel chemotherapy compared to those women with stage IIIC ovarian HGSC with only peritoneal involvement (IP+/RP−) who were treated similarly. Methods: We performed a retrospective, multicenter study with the participation of five gynecological cancer centers. First, the stage IIIC ovarian HGSC patients were classified into optimally or maximally debulked cohorts. Then, in each cohort, the patients were divided into two groups; the IP+/RP− group included those women with transcoelomic spreading outside the pelvis with no nodal disease, and the IP+/RP+ group included those patients with transcoelomic dissemination outside the pelvis in addition to a positive nodal status. The survival outcomes were compared between the two groups in each cohort. Results: A total of 405 ovarian HGSC patients were analyzed. In the optimally debulked cohort (n = 257), the progression‐free survival (PFS) and overall survival (OS) medians for the IP+/RP− group (n = 69) were 24 and 57 months, respectively, compared to 21 and 58 months, respectively, for the IP+/RP+ group (n = 188) (P = 0.78 and P = 0.40, respectively). In the maximally debulked cohort (n = 148), the PFS and OS medians for the IP+/RP− group (n = 55) were 35 and 63 months, respectively, compared to 25 and 51 months, respectively, for the IP+/RP+ group (n = 93) (P = 0.49 and P = 0.31, respectively). Conclusion: Our findings indicated no survival differences between the IP+/RP− and the IP+/RP+ groups. [ABSTRACT FROM AUTHOR]