Exercise-induced bronchospasm (EIB) commonly affects patients with asthma. However, the relationship between EIB and asthma control remains unclear. Exercise limitation due to asthma might lead to reduced physical activity, but little information is available regarding obesity and EIB in asthma. A recent survey evaluated the frequency of EIB and exercise-related respiratory symptoms in a large number of patients with asthma. The survey results were reanalyzed to address any relationship between EIB and asthma control and obesity. A nationwide random sample of children aged 4-12 years (n = 250), adolescents aged 13-17 years (n = 266), and adults aged ≥18 years (n = 1001) with asthma were interviewed by telephone. Questions in the survey addressed asthma symptoms in general, medication use, and height and weight. Asthma control was categorized using established methods in the Expert Panel Report 3. Body mass index (BMI) was calculated using standard nomograms and obesity was defined as a BMI ≥ 30 kg/m(2). Most children (77.6%), adolescents (71.1%), and adults (83.1%) had either "not well" or "very poorly" controlled asthma. Children with "not well" controlled asthma reported a history of EIB significantly more often than those with "well" controlled" asthma. Asthma patients of all ages who had "not well" and "very poorly" controlled asthma described multiple (four or more) exercise-related respiratory symptoms significantly more often than those with "well-controlled" asthma. Obesity was significantly more common in adolescents with "not well" and "very poorly" controlled asthma and adults with "very poorly" controlled asthma. Children, adolescents, and adults with asthma infrequently have well-controlled disease. A history of EIB and exercise-related respiratory symptoms occur more commonly in patients with not well and very poorly controlled asthma. Obesity was found more often in adolescents and adults, but not children, with asthma, which was not well and very poorly controlled.