['Cardiopulmonary exercise testing (CPET) can identify patients at risk of adverse post-operative outcomes following major abdominal surgery including bariatric surgery. Scoring systems that also aim to predict post-operative outcome in this group include the validated obesity surgery mortality risk score (OSMRS). This study aims to investigate if CPET has additive value to other scoring systems in predicting post-operative outcomes following bariatric surgery.', 'Data was collected retrospectively on 398 patients who underwent CPET between October 2008 and April 2013. CPET data, medical history, complication rates and length of stay (LOS) were obtained from patient records. Data was analysed to investigate the relationship between CPET and other scoring systems with post-operative outcome.', 'Two hundred and fifty patients underwent Roux-en-Y gastric bypass or sleeve gastrectomy. Median LOS was 4\xa0days (IQR 4-6\xa0days) and 41 patients (16.4\xa0%) developed a complication. Adjusted data showed a risk difference for complications of 17\xa0% (95\xa0% CI 9-25\xa0%) between high- and low-risk patients stratified by OSMRS alongside a 27\xa0% (95\xa0% CI 12-45\xa0%) longer LOS. Variation in AT or peak VO'] Does cardiopulmonary Exercise Testing have no Additive Incremental Value to Standard Scoring Systems when Risk Stratifying for Bariatric Surgery?