One of the major problems in the management of asthma is that of infection. Its role may be causal, as for instance in the so-called “asthmatic bronchitis” and certain instances of chronic bronchitis with wheezing. In atopic bronchial asthma, it may act solely as a precipitating factor, whereas in the older patient it may act as an allergen. Whatever its role in a particular case, it must be prevented if at all possible, and if not, then aborted promptly.