Asthma is a chronic inflammatory airway disease characterized by reversible obstruction. The cause(s) of asthma are still an area of active investigation in many laboratories across the world, but to date the pathogenesis has remained obscure. It is likely that asthma is the final common pulmonary expression of multiple factors that lead to airway hyperresponsiveness, some inherited and some environmental, which differ in different individuals. It is clear that respiratory infections play a major role in the development of asthma during childhood. However there are seemingly contradictory data suggesting on the one hand that exposure to bacterial products, e.g. lipopolysaccharide, and viral infections, e.g. participation in daycare, during early childhood can be protective, but on the other hand there is well-documented association of the development of airway hyperreactivity following infections with viruses such as respiratory syncytial virus and atypical bacterial infections, particularly with Mycoplasma pneumoniae. New studies, suggest that M. pneumoniae is present in the airways of a substantial proportion of the population, bringing up the possibility that the persistent presence of the organism may contribute to the asthmatic phenotype in a subset of patients. This review will examine the current data regarding a possible role for M. pneumoniae in chronic asthma. © 2013 Bentham Science Publishers.