Allergic reactions due to insect stings with sometimes life-threatening symptoms, are very relevant in adult patients as well as in children. According to the currently available literature, insect stings in adults are the most frequent cause of severe anaphylactic reactions, whereas in childhood they are the second most frequent cause after food allergens. The specific immunotherapy is a very effective therapeutic option in patients with hymenoptera venom allergy, which is also very well tolerated. Many patients can be successfully treated and severe side effects are rarely seen. In most cases only local swelling occurs at the injection site, whereas systemic reactions are uncommon, especially in children. Due to the fact that general measures (e.g. prescription of an emergency kit and avoidance behavior) cannot prevent the occurrence of fatal reactions, a specific immunotherapy should be initiated when the indications can be proven. The diagnostic procedure consists of the determination of specific IgE antibodies against bee or wasp venom (total venom or recombinant allergen components of the venom) as well as skin testing and a positive history of systemic reactions (in children generally beyond skin symptoms). The diagnostic routine also includes the determination of the baseline mast cell tryptase concentration in serum as a sign of underlying mast cell disease and a potential individual risk factor and a physical examination for skin signs of mast cell disorders.