Since eosinophils are prominent in allergic inflammation, investigators became interested in how these cells accumulate in tissues and their role within the inflammatory cascade. There is increasing evidence from several laboratories that eosinophil numbers are regulated in vivo, not only by eosinophil production in the bone marrow, but also by the amount of eosinophil apoptosis. Moreover, it has been directly demonstrated that eosinophil apoptosis is delayed in allergic inflammatory sites, and that this mechanism contributes to the expansion of these cells in tissue. In this article, we review recent studies that shed light on the intracellular pathways that control eosinophil apoptosis.