Aim: The aim of this study conducted in 2013–2015 was to compare the efficacy of two laparoscopic bariatric procedures, i.e., Roux-en-Y gastric bypass (RYGB) and sleeve gastrectomy (LSG) in terms of body mass reduction and improvement in carbohydrate and lipid metabolism. Material and methods: The study group consisted of 20 patients subjected to RYGB (Group I) and 20 patients subjected to LSG (Group II) procedures. Body mass and fasting concentrations of glucose, insulin, glycated hemoglobin, total cholesterol, HDL, LDL and triglycerides were evaluated on the day preceding surgery and 1, 3 and 6 months thereafter. BMI, HOMA-IR and HOMA-B were calculated as well. Results: The reduction of BMI, glucose, insulin, glycated hemoglobin, triglycerides levels as well as HOMA-IR, and HOMA-B indexes and increase of HDL were observed in both groups 6 months after surgery. No reduction of both total cholesterol and LDL concentrations was obtained in both groups. The differences of studied parameters in both groups were not statistically significant. Conclusions: RYGB and LSG are equally effective in terms of body mass reduction, improvement of carbohydrates and lipid metabolism assessed 6 months after surgery.