Obesity is an epidemic of the modern age. Currently in Croatia 20% of men and women are considered obese, while 63% of men and 54% of women are considered overweight. It is interesting to note that incidence levels of obesity are currently stagnating, but incidence od extreme obesity is on the rise. Most obese people try to treat their condition with numerous and often unsuccessful reduction diets, which often fail either out of lack of will or because of a bad diet program. For motivated obese individuals possible solution can be found in bariatric surgery. Development of bariatric surgery started in the 1950s and to this day it developed into a respectable branch of abdominal surgery. Postoperative results are often dramatic as they lead to greater and long-term sustainable weight loss in comparisson to classic reduction diets. Not everyone is a candidate for bariatric surgery, but only those with body mass index greater than 40 kg/m2 or those with body mass index greater than 25 kg/m2 but at the same time suffer from obesity induced life limiting conditions like cardiovascular diseases. It is generally accepted in the surgical community that all patients have to have a history of unsuccesful reduction dieting in order to be considered a candidate for surgery. For an obese person to undergo a surgical procedure it must be first aproved by a council of specialists which consist of a internal medicine specialist, a surgeon, a psychiatrist and a nutritionist.Basis of bariatric surgery is limiting the ability of the gastrointestinal tract to digest and absorb nutrients and to make a person feel full earlier into the meal. That is accomplished, in general, by reducing the size of the stomach and/or bypassing parts of the small intestine which efectively reduces the apsorption area of the intestines. 36 Most common type of weight loss surgery in the world is Roux-en-Y gastric bypass. In this surgical procedure size of the stomach is artificially reduced and a part of the small intestine is bypassed in a way that it forms a structure shaped like the letter „Y“ in which duodenum and part of the jejunum form the biliopancreatic limb which serves only as a passage for digestive juices, while the rest of the jejunum forms the alimentary limb through wich the food is passed. The two limbs are connected through an artificial anastomosis and the small intestine after it we call the common limb. Since recently there is also a surgical procedure called laparoscopic gastric bypass in which the continuity of the small intestine isn't divided and only a gastrojejunostomy is formed.Out the other more notable methods we must mention laparoscopic gastric banding, laparoscopic sleeve gastrectomy and duodenal switch. Results of all types of surgeries are generally more succesful than those of reduction diets and researches show excess weght loss up to 40-55% in a 3-year period. Additionally, patients health is also greatly improved since many obesity related comorbidities, like type two diabetes, are improved or resolved postoperatively.