Over the past few years, obesity has become a major clinical and population concern in the majority of developed countries. Obesity leads to significant systemic disorders, such as hypertension, hypercholesterolemia, hypertriglyceridemia and insulin resistance, and also increases the risk of developing cardiovascular diseases (ischemic heart disease, ischemic stroke), metabolic diseases (type 2 diabetes), certain types of cancer, and degenerative bone disorders (osteoarthritis). Health hazards associated with epidemic of obesity and potential benefits of weight loss have spurred interest in new treatment methods. Bariatric surgical procedures constitute a recognized alternative in cases where conservative management of obesity fails. Several bariatric operations can be distinguished: restrictive procedures, such as adjustable gastric band (AGB) and vertical banded gastroplasty (VBG); predominantly malabsorptive procedures, such as biliopancreatic diversion (BPD), and a combination of both methods, such as Roux-en-Y gastric bypass. The adverse consequences of surgical treatment of obesity include i.a.: intestinal anastomotic leakage, impaired intestinal permeability and internal hernia, dilatation of the stomach, gastrointestinal anastomotic stenosis, marginal ulceration, incisional hernia. Basic knowledge of procedures in the surgical treatment of obesity is of vital importance for the radiologist during evaluation of upper gastrointestinal tract in the early and late postoperative period, allowing correct interpretation of acquired images as well as recognition of typical complications.