Epidemiology and especially the natural history of Hymenoptera allergy form the background that is essential to improving the clinical management of insect venom allergic patients. This review focuses on the emergence of recent data which could help provide further enlightenment in this field. The latest data on the extent of the disease, the risk factors for sensitization and for local, systemic and fatal reactions after a hymenoptera sting are reviewed. The emerging problems concerning asymptomatic sensitization, the meaning of constitutively elevated tryptase serum levels and the persisting widespread poor awareness of available therapies in Hymenoptera allergic patients are particularly emphasized. The assessment of the risk for systemic reaction in skin-positive subjects with a negative case history, and the suggestion of the baseline serum tryptase level as a risk factor for reaction severity after a sting, are the most important clinical implications of the latest studies. The genetic and environmental factors involved in the persistence of venom specific immunoglobulin E after a sting and the factors which orient towards a systemic or a large local reaction after apparently the same sting remain open questions.