Background: Current studies mainly focus on total weight loss and comorbidity reduction. Only a few studies compare Quality of Life (QoL) after sleeve gastrectomy (SG) and Roux-en-Y gastric bypass (RYGB). This study was conducted to examine the extent of improvement in QoL on different domains after primary bariatric surgery and compare these results to Dutch reference values. Methods: The study included prospectively collected data from patients who underwent primary bariatric surgery in five Dutch hospitals. The RAND-36 questionnaire was used to measure the patient’s QoL; preoperatively and twelve months postoperatively. Postoperative scores were compared to Dutch reference values, standardized for age, using t-test. A difference of more than 5% was considered a minimal important difference. A multivariate linear regression analysis was used to compare SG and RYGB on the extent of improvement, adjusted for case-mix factors. Results: In total, 4864 patients completed both the pre- and postoperative questionnaire. Compared with Dutch reference values, patients postoperatively reported clinically relevant better physical functioning (RYGB + 6.8%), physical role limitations (SG + 5.6%; RYGB + 6.2%) and health change (SG + 77.1%; RYGB + 80.0%), but worse general health perception (SG − 22.8%; RYGB − 17.0%). Improvement in QoL was similar between SG and RYGB, except for physical functioning (β 2.758; p-value 0.008) and general health perception (β 2.607; p-value < 0.001) for which RYGB patients improved more. Conclusions: SG and RYGB patients achieved a better postoperative score in physical functioning, physical role limitations and health change compared to Dutch reference values, and a worse score in general health perception.@en