The objective of this study is to characterize patterns of utilization of adjuvant chemotherapy (CT) and radiotherapy (RT) in the posthysterectomy management of uterine carcinosarcoma (UCS) in the United States. We queried the National Cancer Database for women diagnosed with UCS between 2004 and 2012 and undergoing hysterectomy. Logistic regression was performed to identify sociodemographic, facility-specific, and treatment-related predictors of receiving multiagent chemotherapy, external beam radiotherapy (EBRT), or brachytherapy (BT). In total 4272 patients were included, with 2 in 5 (40.5%) receiving no adjuvant therapy. Regarding RT, 2357 (55.1%) received neither EBRT nor BT, 929 (21.7%) received EBRT alone, 518 (12.1%) received BT alone, and 468 (11.0%) received EBRT+BT. Most women (70.8%) received no CT, a minority (1.5%) received single-agent CT, and the rest (27.8%) received multiagent chemotherapy. Logistic regression demonstrated disparities in receipt of adjuvant therapies by age, diagnosis year, insurance, facility volume, facility type, stage, and margin status, with patients with positive surgical margins less likely to receive BT. Following hysterectomy for UCS, a large proportion of women receives no CT and no RT in the United States. Multispecialty evaluation is critical for individualization of therapy and may address disparities in this aggressive disease.