OBJECTIVE: The optimal management of patients with stage I uterine papillary serous carcinoma (UPSC) is unclear. We sought to determine whether outcomes of women with surgical stage I UPSC differ with and without adjuvant therapy. METHODS: Retrospective multi-institution analysis of women with stage I UPSC surgically staged from 1976 to 2006. Inclusion criteria: comprehensive staging procedure including hysterectomy, bilateral salpingo-oophorectomy, selective pelvic/aortic lymphadenectomy, peritoneal cytology. Recurrence and survival were analyzed using Kaplan–Meier method. RESULTS: Of 83 women with stage I UPSC, 36 (43%) received adjuvant therapies (23% radiotherapy, 3% chemotherapy, 15% chemotherapy and radiotherapy, 2% progestins). Three-year overall (OS) and progression-free survival (PFS) were 80% and 68%, respectively. Three-year OS and PFS by adjuvant treatment were observation (N = 47) 86% and 78%, radiotherapy (N = 17) 63% and 44%, chemotherapy with or without radiotherapy (N = 17) 92% and 76%, respectively. Of the 18 recurrences, 9 (50%) included an extrapelvic component. Local recurrence was 2/30 (7%) following adjuvant radiotherapy and 7/53 (13%) without radiotherapy (p = 0.48). Recurrence was higher in stage IB/IC (15/51, 29%) compared to stage IA (3/32, 9%). There has been one recurrence (5%) among the 22 women observed with stage IA disease. CONCLUSION: In this largest reported series of women with surgical stage I UPSC, the high recurrence (29%) among patients with stage IB/IC disease highlights the need for clinical trials to test new therapeutic approaches. Surgically staged patients with IA disease had good prognosis. These data suggest that radiotherapy alone is not effective, that systemic therapy is needed, and that observation could be considered in patients with stage IA disease.