Background: Endometrial cancer is one of the most common gynecologic malignancies in the world. however, the effects of systemic chemotherapy are limited. The combination of targeted therapy with immunotherapy is a new research field in the treatment of malignant tumors. Anlotinib is a novel tyrosine kinase inhibitor with highly selective inhibition effects on multi-targets, especially on vascular endothelial growth factor receptor, Platelet-derived growth factor receptor and Fibroblast growth factor receptor. Sintilimab is a highly selective, fully humanized, monoclonal antibody, which blocks the interaction between Programmed death 1 and its ligands. This research aimed to evaluate the efficacy and safety of the combination of anotinib and sintilimab in patients with recurrent advanced endometrial cancer. Methods: Patients who received at least one platinum-based systemic chemotherapy, had an Eastern Cooperative Oncology Group performance status of 0 or 1 were considered eligible for enrollment. Sintilimab was administered intravenously (200mg，q3w); anlotinib was taken orally (12mg qd, d1-14, 21 days per cycle). The treatment was continued until disease progression, death or intolerant toxicity. The primary endpoint was objective response rate (ORR) and the secondary endpoints included duration of response, disease control rate (DCR), progression-free survival (PFS), overall survival and safety. Results: From November 2019 to to September 2020, 23 patients with a median age of 56 years (range: 37-70), FIGO stage IA (21.7%), IB (8.7%), II (4.4%), IIIA (13.1%)，IIIC (30.4%), IVB (21.7%) were enrolled. Among these participants, 22 patients were evaluable. The therapeutic evaluation showed the incidence of complete response, partial response, stable disease and progression disease was 13.6%, 63.7%, 13.6% and 9.1% respectively, yielding the ORR of 77.3% (95%CI: 58.3%-96.3%) and the DCR of 91.7% (95%CI: 79.8%-100%). ≥1 and ＜1 Combined Positive Score of PD-L1 expression were observed in 66.7% (14/21) and 33.3% (7/21) patients respectively, and the ORR was 92.9% (95%CI: 77.4%-100%) and 57.1% (95%CI: 18.4%-90.1%) in the two groups. The median time of the first response was 1.5 months (range, 0.7-12.8). The median PFS was not reached. Most of the occurring adverse events (AEs) were grade 1 or 2. Grade 3 AEs included ileus (4.3%), immune myocarditis (4.3%) immune peritonitis (4.3%), hand-foot syndrome (8.7%), neutropenia (4.3%), neutrophils decrease (4.3%), and hypertension (4.3%); Grade 4 AE was lymphocytosis (4.3%). Neither unexpected safety signals nor treatment-related death occurred. Conclusions: Anlotinib plus sintilimab showed a promising antitumor activity with a favorable toxicity profile for patients with recurrent advanced endometrial cancer. We will report more data in the future. Clinical trial information: NCT04157491