Ghrelin is a 28 amino acid peptide hormone regulating food intake and stimulating releasement of growth hormone. It is produced in a distinct endocrine call known as X/A - like cells. The most abundant source of this very important factor in energy homeostasis is gastric fundus. Regulatory mechanisms of ghrelin synthesis and secretion in physiological and pathological states are not discovered completely. The aim of our study was evaluation of the activity of gastric X/A-like cells in obese patients before and after the most popular surgical bariatric procedures - Roux - Y Gastric Bypass (RYGB) and Laparoscopic Adjustable Gastric Banding (LAGB). Obese patients in number 18 took part in the study. LAGB was performed in 7 patients and RYGB in 11 patients. Peripheral blood was taken from each patient before operation and first day, seventh day, one month and three months after surgery. Ghrelin level was determined by RIA technique. The specimen of stomach was taken from circular stapler after gastrojejunostomy during RYGB and immunohistochemical study of gastric mucosa, using the EnVision method and specific monoclonal antybodies against ghrelin was performed. The intensity of ghrelin-immunoreactivity in X/A-like cells was analyzed using Olympus Cell D image analysis system. Efficiency of bariatric procedures was estimated by EWL- excess weight loss. We observed very strong immunohistochemical reactions of gastric X/A-like cells, accompanied by lower ghrelin plasma concentration, in comparison to the control group. LAGB procedure induced increase of ghrelin plasma level while RYGB procedure induced decrease of this hormone. The main finding of the present study is the hypoactivity of gastric X/A-like cells in obese patients in comparison to the control group.