Background: Childhood obesity has become a global epidemic. It is related to several chronic diseases such as essential hypertension, type 2 diabetes mellitus, and renal disease. The relationship between the degree of obesity and lung functions is well defined in adults, but limited information is available about the childhood period. Aims: This study aims to determine the impact of the degree of obesity on the pulmonary functions of school children and adolescents. Study Design: Cross sectional study. Methods: Included in the study were a total of 170 school children and adolescents (9-17 years old) referred to our paediatric outpatient clinic. Of these subjects, 42 were lean and non-obese (BMI %