Elderly patients with rectal cancer have been excluded from randomized studies, thus little is known about their early postoperative mortality, which is critical for informed consent and treatment decisions. This study examined early mortality after surgery in elderly patients with locally advanced rectal cancer (LARC). Using the National Cancer Database, we identified patients aged ≥75 years, diagnosed with clinical stage II/III rectal cancer who underwent surgery in 2004 through 2015. Descriptive analyses determined proportions and trends and multivariable logistic regression analyses were performed to determine factors associated with early mortality after rectal cancer surgery. Among 11,794 patients with rectal cancer aged ≥75 years, approximately 6% underwent local excision and 94% received radical resection. Overall 30-day, 90-day, and 6-month postoperative mortality rates were 4.2%, 7.8%, and 11.5%, respectively. Six-month mortality varied by age (8.4% in age 75-79 years to 18.3% in age ≥85 years), and comorbidity score (10.1% for comorbidity score 0 to 17.7% for comorbidity score ≥2). Six-month mortality declined from 12.3% in 2004 through 2007 to 10.2% in 2012 through 2015 (Ptrend=.0035). Older age, higher comorbidity score, and lower facility case volume were associated with higher 6-month mortality. Patients treated at NCI-designated centers had 30% lower odds of 6-month mortality compared with those treated at teaching/research centers. Six-month mortality rates after surgery among patients aged ≥75 years with LARC have declined steadily over the past decade in the United States. Older age, higher comorbidity score, and care at a low-case-volume facility were associated with higher 6-month mortality after surgery. This information is necessary for informed consent and decisions regarding optimal management of elderly patients with LARC.