Background and Objectives: Colorectal cancer incidence increases with age; therefore, rectal cancer treatment in elderly patients is increasingly common. Surgery is a common rectal cancer treatment, and the risks involve complicated surgical decisions. There are currently few surgical outcome data for rectal cancer in elderly patients. The aim of this study is to identify new perioperative risk factors that could be associated with higher 30-and 180-day mortality in elderly patients in good clinical condition considering traditional perioperative risk scores and to develop a risk score.Methods: A single-centre, retrospective cohort study was performed by reviewing the medical records of patients from the National Cancer Institute of Brazil aged 80 years or older who electively underwent rectal cancer surgery; several independent variables correlated with death from all causes at 30 and 180 days were studied.Results: Multivariate analysis found new variables (CEA, albumin and reoperation) that had independent correlations with increased 30-and 180-day mortality. A clinical risk score was developed with survival profiles ranging from 29.3% to 97.2% within 30 days and 2.45% to 91.8% within 180 days.Conclusions: This score can aid in deciding whether a patient should undergo rectal cancer surgery.