Background(#br)Elderly patients (65 years of age and older) undergo an increasing number of operations performed annually in the US and they present with unique healthcare needs. Preventing postoperative readmission remains an important challenge to improving surgical care. This study examined whether geriatric-specific variables were independently associated with postoperative readmissions of elderly patients.(#br)Methods(#br)The American College of Surgeons (ACS) Geriatric Surgery Research File (GSRF) was joined with the ACS NSQIP Participant Use Data Files for 2014 to 2016. This data set included 13 GSRF variables and 26 ACS NSQIP variables. Associations between clinically relevant variables and readmission were tested with multivariable logistic regression.(#br)Results(#br)The data... represented 6,039 general surgery patients age 65 years and older. Fifty-eight percent of patients had colorectal operations, 19% pancreatic or hepatobiliary, 15% hernia, 4% thyroid or esophageal, and 3% had appendix operations. Twenty-four percent of patients experienced an NSQIP-defined 30-day postoperative complication and 3% died within 30 days after operation. Eleven percent of patients had unplanned 30-day readmission. Standard NSQIP variables, including 30-day composite morbidity (odds ratio [OR] 5.11; 95% CI, 4.24 to 6.16; p < 0.001), reoperation (OR 2.8; 95% CI, 2.07 to 3.79; p < 0.001), and steroid use (1.42; 95% CI, 1.03 to 1.96; p = 0.03) were associated with readmission. In addition, GSRF variables, including incompetent on admission (OR 1.63; 95% CI, 1.11 to 2.38; p = 0.01), fall risk at discharge (OR 1.42; 95% CI, 1.11 to 1.82; p = 0.005), use of mobility aid (OR 1.26; 95% CI, 1.02 to 1.56; p = 0.03), and discharged home with skilled care (OR, 1.22; 95% CI, 1.0 to 1.49; p = 0.04) were associated with readmission.(#br)Conclusions(#br)Four GSRF and 3 current standard ACS NSQIP variables were important in the evaluation of postoperative readmission of elderly patients. Geriatric-specific variables contributed to the explanation of the relationship between clinical variables and readmissions in elderly surgical patients.