The obese patient constitute the group with high perioperative risk due to more respiratory and cardiovascular disorders. The respiratory disorders deepen during postoperative period.The aim of the study was an assessment of changes in ventilation lung activity after classic and laparoscopic bariatric operations.Material and methods. For the lung activity assessment the measurement of pick expiratory flow was used before operation, in the first and third twenty-four hours after operation. Moreover, before and in the first twenty-four hours after operation a spirometry was performed. The forced vital capacity (FVC), 1 second forced expiratory volume (FEV1) and Tiffenau index (FEV1/FVC) were estimated in the study. 54 persons were included in batriatric operations. The first group was formed by the patients after vertical banded gastroplasty (VBG), the second after laparoscopic vertical banded gastroplasty (LVBG), the third one after laparoscopic adjustable gastric banding (LABG).Results. The following average results were gained: first group-PEF before operation 399 liter per minute, in the first twenty-four hours after operation 195 liter per minute and in the third twenty-four hours 282 liter per minute. FEV1 before operation 2.6 liter, in the first twenty-four hours 1.5 liter, FVC before 3.5 liter and after operation 2liter. Tiffenau index before 86%, after 85%. The second group PEF before operation 446 liter per minute, in the first twenty-four hours 326 liter per minute in the third twenty-four hours 409 liter per minute, FEV1 before 3.6 liter, after 2.6 liter, FVC before 3.9 liter, after 2.7 liter, Tiffenau index before 92%, after 96%. The third group PEF before 460 liter per minute, in the first twenty-four hours 340 liter per minute, in the third twenty-four hours 430 liter per minute, FEV1 before 3.2 liter, after 3.1 liter, FVC before 4.5 liter, after 3.6 liter, Tiffenau index before 90%, after 90%.Conclusions. The bariatric operations reduce ventilation lung activity. After classic bariatric surgery respiratory disorders are longer and become more intense. Independently of bariatric operation's method all respiratory disorders have a restrict type.