- To determine whether obesity among children is associated with an increased incidence of asthma. Five thousand nine hundred eighty-four children participated in a lung health study in the Ashkelon region, Israel. A lung health questionnaire was completed and they underwent spirometry. Body mass index (BMI) was then calculated for each child. Three hundred two children (5.05%) were above the 95th percentile for BMI and considered obese. Obese children tended to wheeze more than the non-obese children 14.5% vs. 10.5%, respectively (p<0.038). Asthma (physician diagnosis) was diagnosed more often among obese children than non-obese 7.2% vs. 3.9%, respectively (p<0.008). Inhaler use was more prevalent among obese children than non-obese 15.9% vs. 8.8%, respectively (p<0.001). Bronchial hyperreactivity was significantly greater among the non-obese asthmatic children compared with their obese counterparts, 352 (51.4%) vs. 10 (27.8%), respectively (p<0.001). Chest symptoms and asthma were more frequent in obese than non-obese boys. Asthma, wheezing, and inhaler use were more common in obese children than in non-obese children. Symptoms were more prevalent among obese boys. Increasing BMI among children is a risk factor for asthma, which may in reality be obesity-related chest symptoms that mimic asthma.