Immunoglobulin (Ig) E plays a key role in the pathogenesis of allergic disease. The studies on the cellular basis of IgE regulation have provided important insights into a disease process which affects a considerable proportion of the population worldwide. More recently, the molecular events underlying IgE synthesis have been actively investigated. In this review, we will discuss the cells, the cytokines, the signal transduction events and the molecular mechanisms involved in human IgE synthesis as well as therapeutic approaches directed at the abrogation of these processes.