OBJECTIVES: This study was conducted to compare the improvement of quality of life in patients treated with either bariatric surgery or conventional therapy in obese Korean people. METHODS: The quality of life was investigated for 53 patients who underwent bariatric surgery and 25 patients who were treated by conventional therapy in 7 tertiary medical centers. The quality of life was measured right before treatment and after at least five month of that by self-report instruments; The instruments for measuring quality of life were EuroQol-5D (EQ-5D), Impact of Weight on Quality of Life-Lite Questionnaire (IWQOL-Lite), and Obesity-related Problem scale (OP-scale). Through the medical chart review, percent weight change from baseline was investigated. The difference of QOL improvement from baseline between two treatments was compared using the t-test. The relationship between weight control and QOL improvement was also investigated. RESULTS: The improvement of QOL was 0.174 in EQ-5D index score and 24.6 in VAS score for bariatric surgery, and 0.071 and 17.8 for conventional therapy. QOL score using IWQOL-Lite and OP-scale were 33.4 and 39.3 for bariatric surgery and 14.3 and 9.6 for conventional therapy. Measuring by obesity-specific questionnaires (IWQOL-Lite and OP-scale), the improvement of QOL before and after treatments was significantly higher in bariatric surgery than conventional therapy, but the general questionnaires (EQ-5D 3 level and EQ-VAS) did not show. The percent weight change from baseline had positive correlation with the improvement of QOL.  CONCLUSIONS: The improvement in quality of life was significantly higher among bariatric surgery group compared with the conventional therapy group, especially for the obesity specific questionnaires.