Background: Obesity is an important, worldwide public health problem. Obesity affects all body systems, but mainly cardiovascular and respiratory systems. We aimed to investigate the change in respiratory functions due to both the decrease in Body Mass Index (BMI) and laparoscopic obesity surgery that is used in obesity treatment. Methods: Patients were selected who applied to Ondokuz MayÄ±s university general surgery clinics and referred to pulmonary medicine clinics for preoperative evaluation. 32 patients applied for laparoscopic obesity surgery with BMI greater than 40 kg by m2 monitored. Pulmonary symptoms of patients were evaluated pre operatively and post operatively, their BMIs were calculated and pulmonary function tests, lung diffusion testing and 6 Minutes Walking Test (6 MWT) were applied. The data obtained at the end of the study were assessed under computer setting by SPSS 15.0 program. Chi Square, Mann Whitney U, Wilcoxon Signed Ranks, Paired T and Student T tests were used in statistical analysis of data. Results: Average age of patients was 35.3 plus or minus 9.3 and 28.1 percentage of them (n equal to 9) were men, 71.9 percentage (n equal to 23) of them were women. The fact that majority of patients who participated the study were women was related with more frequent morbid obesity in women in general we also saw that women applied to hospital for obesity surgery at a higher ratio. When pre operative and post operative data were compared, BMI of patients decreased by 28 percentage, FEV1 value, FEV1 percentage, FVC value and FVC percentages increased by 11.9 percentage, 14.8 percentage, 14.8 percentage and 17.3 percentage respectively, these results were statistically significant. Conclusion: Recovery in respiratory functions due to decrease in BMI was observed after laparoscopic sleeve gastrectomy in obesity.