Background: In almost six decades different surgical techniques have been developed to treat patients with morbid obesity. Various surgical techniques are generally divided with respect to their effect into restrictive, malabsorbtive and humoral and a combination of these. Surgically modified human metabolism ameliorates metabolic diseases, particularly diabetes, even in non-obese patients. The understanding of metabolic effects changed the traditional paradigm of bariatric surgery from simple weight-loss procedure to metabolic surgery affecting whole-body metabolism. Proper surgical technique for individual patient is the most important factor influencing long- term results, comorbidities and quality of life. Recommendations for patient selection, surgical methods and pre- and postoperative patient management are to be respected. Metabolic surgery principles and current concepts are presented.