Background: Renal sarcomas are a rare malignancy in adults and have been inadequately evaluated on a US national level regarding epidemiology, treatment, and outcomes. Methods: The 2004-2016 NCDB and SEER databases were queried for adult patients diagnosed with sarcomas of renal origin. Age-adjusted incidence rates were derived from the SEER database. Overall survival (OS) was assessed using multivariable Cox proportional hazards models adjusting for demographics, tumor and treatment variables. Results: 1,279 renal sarcomas comprising 39 subtypes were reported from 2004-2016, contributing 0.3% of all NCDB renal malignancies. As shown in the table below, the most common subtypes were leiomyosarcoma (LMS), angiosarcoma (AS), malignant rhabdoid tumor (MRT), dedifferentiated liposarcoma (DL) and primitive neuroectodermal tumors (PNET). Over the study period, renal sarcoma incidence rates remained constant at 0.5 cases / 1 million citizens. Sex-specific incidence differences were evident with female predominance for LMS, and male predominance for AS. Age at diagnosis and tumor diameter varied according to sarcoma subtypes: for example, median age in LMS was 62y compared to 30y in Ewing sarcoma patients; median tumor diameter was 18cm for solitary fibrous tumors and 7.5cm for synovial sarcoma. Renal sarcoma was staged as T3 in 33.3% and T4 in 14.2%, while distant metastases were evident in 29.1% of cases at diagnosis. Most T1-T3 stage renal sarcomas underwent surgical resection (992/1098, 84%), compared to 71% for T4 renal sarcomas (128/181). Systemic therapy was administered in 32.1% of renal sarcoma cases (23.5% combined with surgical resection). Renal sarcoma 1-,2-, and 5-year OS rates were 48%, 24%, and 13%. OS was worse for T4 vs T1-3 sarcomas (HR=1.6, p<0.001), and cases with distant metastases vs none (HR=3.2, p<0.001). As summarized in the table, OS varied according to sarcoma subtypes with worse OS for AS compared to PNET (HR=1.5, p=0.04). Conclusions: Accounting for 0.3% of renal malignancies in adults, renal sarcomas include 39 different histological subtypes with distinct demographics, tumor parameters and outcomes. Renal sarcomas commonly present with advanced T stage at diagnosis and are treated with surgical resection with or without systemic therapy.