OBJECTIVES:  The aim of the study was to compare the cost-effectiveness of bariatric surgery with non-surgical treatment of morbid obesity from the perspective of a healthcare payer in Poland. METHODS: A health state transition (Markov) model simulating the treatment of obesity and obesity-related comorbidities over the course of 20 years was developed. All the results described in this analysis were generated for a population consisting of morbidly obese patients – BMI ≥40, or BMI ≥35 with obesity-related comorbidities. Various combinations of the following types of bariatric surgery were compared with conventional treatment: adjustable gastric banding (AGB), gastric bypass (GBP) and sleeve gastrectomy (SG). Polish market share data were developed based on IFSO 2014 survey and Diagnosis-related group (DRG) catalogue. Cost data were estimated on the basis of the National Health Fund (NHF) data, publicly available Ministry of Health (MoH) data and information obtained from the literature search. Other model inputs i.e. utility/disutility values and probabilities of transitions between health states were derived from the literature. Data are presented in EUR (1 EUR = 4.00 PLN). RESULTS: Over the course of 20 years, bariatric surgery was projected to have better net clinical benefits over conventional treatment with a substantially greater number of quality-adjusted life years (QALYs) gained (depending on the analyzed surgical technique, QALY gains were 2.42 to 2.55). There were also cost savings achieved by bariatric surgery (201.50 EUR to 1,143.75 EUR). The ICER for bariatric surgery compared to conventional treatment was dominant. Bariatric surgery was associated with a reduction of morbidity and cost savings associated with treatment of obesity-related comorbidities i.e. cancer, diabetes and cardio-vascular diseases (stroke, myocardial infarction). CONCLUSIONS: Bariatric surgery provides greater effectiveness at a lower cost compared with non-surgical treatment of morbid obesity.