Background: The rising prevalence of asthma worldwide may be associated with the rising prevalence of obesity in developed nations. Although several studies have suggested a relationship between asthma and obesity, controversy still remains. The aim of this study was to examine the relationship between obesity and asthmatic factors such as atopy, eosinophilia, serum total Ig E and bronchial hyperresponsiveness in chronic cough patients. Methods: This study was a retrospective, observational study in two centers done between January 2007 and June 2008. The subjects included individuals who had a chronic cough. We examined body mass index (BMI) to measure obesity and pulmonary function. We did a metacholine provocation test for airway hyperresponsiveness (AHR), a skin prick test for atopy, and tests for blood eosinophils and serum IgE. Results: A total of 1022 subjects were included. Airway hyperresponsiveness was not related with obesity (p=0.06), and atopy incidence was significant higher in non obese patients (p=0.00). There was no significant difference in serum IgE and blood eosinophil counts between obese and non obese patients. Forced expiratory volue in one second ($FEV_1$)/forced vital capacity (FVC) was significantly reduced in obese patients (p=0.03), but FEV1 and FVC were no significant difference between obese and non obese patients. Conclusion: There is no relationship between obesity and bronchial hyperresponsiveness. The nonobese group appears to have more atopy. The relationship between obesity and bronchial hyperresponsiveness and atopy need further investigation.