Increase in morbidity and mortality of asthmatics in the world is a cause of concern. Many researchers have described various aspects of etiopathogenesis which has thrown light on the better understanding of asthma. Our experience with nearly 3 lakhs of asthmatic children, over a period of twenty-five years and our studies in Asthma clinic of ICH & HC, Madras generated new ideas to propose a hypothesis on etiopathogenesis of asthma. "Asthma is a disease caused by a specific infective agent in a genetically predisposed individual resulting in altered cellular response initially leading to hyperactive bronchial tree which on exposure to various aggravating factors manifest clinically as recurrent cough, dyspnoea and wheeze". Category of wheezers who manifest asthma is also discussed.