Background Current methods to predict patients' perioperative morbidity use complex algorithms with multiple clinical variables focusing primarily on organ-specific compromise. The aim of the current study was to determine the value of a timed stair climb in predicting perioperative complications for patients undergoing abdominal surgery. Study Design From March 2014 to July 2015, three hundred and sixty-two patients attempted stair climbing while being timed before undergoing elective abdominal surgery. Vital signs were measured before and after stair climb. Ninety-day postoperative complications were assessed by the Accordion Severity Grading System. The prognostic value of stair climb was compared with the American College of Surgeons NSQIP risk calculator. Results A total of 264 (97.4%) patients were able to complete the stair climb. Stair climb time directly correlated to changes in both mean arterial pressure and heart rate as an indicator of stress. An Accordion grade 2 or higher complication occurred in 84 (25%) patients. There were 8 mortalities (2.4%). Patients with slower stair climb times had increased complication rates (p < 0.0001). In multivariable analysis, stair climb time was the single strongest predictor of complications (odds ratio = 1.029; p < 0.0001), and no other clinical comorbidity reached statistical significance. Receiver operative characteristic curves predicting postoperative morbidity by stair climb time was superior to that of the American College of Surgeons risk calculator (area under the curve = 0.81 vs 0.62; p < 0.0001). Additionally, slower patients had greater deviations from predicted length of hospital stay (p = 0.034). Conclusions Stair climb provides measurable stress, accurately predicts postoperative complications, and is easy to administer in patients undergoing abdominal surgery. Larger patient populations with a diverse group of operations will be needed to validate the use of stair climbing in risk-prediction models.