Many elderly patients with cancer experience increased cancer-related morbidity and mortality compared with younger patients. In soft tissue sarcoma, adjuvant radiotherapy is an integral part of definitive therapy for limb preservation. The authors of this report hypothesized that age-related disparities exist in the use of radiation. Surveillance, Epidemiology, and End Results (SEER) data were used to conduct a retrospective cohort study among patients aged ≥ 25 years who were diagnosed from 1998 to 2004 with nonmetastatic, biopsy-proven, high-grade soft tissue sarcoma of the extremities and underwent a limb-sparing procedure. Patients were stratified according to age (ages < 50 years, 50-70 years, and > 70 years). Logistic regression was used to determine the association between age and the receipt of radiotherapy adjusting for histology, tumor location, tumor size, surgery, sex, race, and marital status. A Cox proportional hazards model was used to compare disease-specific and all-cause mortality. Among 1354 eligible patients; 37.1% were aged > 70 years, 44.3% were women, and 84.4% were Caucasian. Although 73.8% of the cohort received radiotherapy, receipt decreased from 78.2% among patients aged < 50 years to 69.6% among patients aged >70 years (test for trend; P = .006). After adjusting for demographic and tumor factors, older patients remained less likely to receive radiotherapy (odds ratio, 0.66; 95% confidence interval, 0.47-0.92) and more likely to experience disease-specific death (hazard ratio, 2.4; 95% confidence interval, 1.4-4.1) compared with the youngest group. Older adults appeared to be less likely to receive definitive therapy for soft tissue sarcoma of the extremities. In the absence of clinical trials and treatment guidelines tailored to this population, under treatment may disadvantage elderly patients, who have increased cancer-related morbidity and mortality.