Primary ovarian serous carcinoma patients presenting with regional lymph node metastasis without extrapelvic peritoneal metastasis are considered International Federation of Gynecology and Obstetrics (FIGO) Stage IIIC. We studied their controversial survival compared with patients with extrapelvic peritoneal metastasis in same Stage IIIC. We included primary peritoneal carcinoma patients with lymph node metastasis to investigate whether primary site of tumor has a prognostic role. Charts of patients treated at the MD Anderson Cancer Center in Houston, TX; from 1992 to 2010 were reviewed. Primary ovarian serous carcinoma patients were grouped into patients with lymph node metastasis without extrapelvic involvement (Group 1, n=13) and patients with additional extrapelvic peritoneal involvement (Group 2, n=43). Group 3 patients (n=38) were selected using similar criteria as Group 2 but with negative lymph nodes. Group 4 patients were those with primary peritoneal serous carcinoma with lymph node metastasis (n=13). Group 1 patients had statistically significant better overall survival compared with the rest of the groups. Overall survival was significantly better in Groups 4 versus 2 and Groups 3 versus 2. Primary ovarian serous carcinoma patients with lymph node metastasis without extrapelvic peritoneal involvement have better survival than those with additional extrapelvic peritoneal involvement. Primary peritoneal serous carcinoma patients with lymph node metastasis have better survival than those with primary ovarian serous carcinoma with peritoneal and lymph node metastasis. Ovarian serous carcinoma patients with extrapelvic peritoneal involvement alone have better survival than those with extrapelvic peritoneal involvement and lymph node metastasis. These findings support the proposition to revise the FIGO staging system, especially for Stage IIIC patients, in order to reflect these prognostic differences.