AIm: To investigate changes in cholecystokinin (CCK) levels after cholecystectomy in patients with IBS and increased on body mass index (BMI). Materials and Methods: We examined and treated 57 patients. The examined patients were divided into two groups depending on the method of chole cystectomy: group 1 included 35 patients who underwent laparoscopic cholecystectomy (LCE), and group 2 consisted of 22 patients who underwent open cholecystectomy (OCE). The level of CCK was determined in blood serum. Results: A correlation was established between BMI and the clinical form of IBS, namely, in patients of group 1, overweight correlated with IBS-D (r=0.86; p<0.01), while in patients of group 2, obesity of the 3rd degree correlated with IBS-constipation (IBS-C) (r=0.90; p<0.01). A significant increase in the level of CCK in the blood serum of the examined patients with IBS and anorexia was established even before the .E. Conclusions: In patients with IBS and GSD, an increase in the level of CCK in the blood serum was found, which increases maximally during cholecystectomy, especially its open form. A positive correlation was established between the level of CCK and the form of IBS, namely r=0.90; p<0.01 for patients with IBS diarrhoea and r=0.96; p<0.01 for patients with IBS-constipation after cholecystectomy.