Mastocytosis is a rare disorder characterized by accumulation of mast cells in tissues. Sixty-five percent of patients with mastocytosis are children. Whereas mastocytosis in adults is usually persistent or progressive, pediatric mastocytosis is often transient and limited. Recent studies suggest that childhood-onset and adult-onset mastocytosis also differ in their pathogenesis. This article reviews the various forms of pediatric mastocytosis with a special focus on new pathogenetic findings.