Allergic reactions to Hymenoptera stings usually present as large local reactions or systemic reactions with symptoms of immediate type allergy (anaphylaxis). In Central Europe they are predominantly elicited by stings of the honeybee or Vespula spp. Acute reactions are managed by symptomatic treatment. Long-term care includes patient education (allergen avoidance, course of action at re-sting) and prescription of an emergency kit for self-treatment. Venom immunotherapy is established as specific treatment for Hymenoptera venom allergic patients. Diagnosis of Hymenoptera venom anaphylaxis is based on history, skin tests and measurement of venom-specific serum IgE antibodies. "False negative" or "false positive" results are possible with all test methods. If standard tests are negative, additional tests using the patient's peripheral blood leucocytes can be useful. Venom immunotherapy is usually well tolerated. After reaching the maintenance dose, therapeutic efficacy should be assessed by a sting challenge test. If the patient again develops a systemic reaction, an increase of the maintenance dose (usually 200 microg are sufficient) nearly always induces protection. In most patients venom immunotherapy can be stopped after (3 to) 5 years. However, if there is an increased risk of sting anaphylaxis due to intense allergen exposure (e.g. in beekeepers) or if there are individual risk factors for particularly severe reactions (especially mastocytosis and/or elevated baseline serum tryptase concentration, severe cardiovascular disease), modifications of the standard venom immunotherapy are necessary.