Wasp and bee stings can lead to allergic reactions, anaphylaxis, Kounis syndrome, toxicity, organ failure and, in rare cases, cardiac arrest. In the Netherlands, fatal complications as a result of wasp or bee stings are rare; here we describe three recent severe cases. We diagnosed two patients with anaphylactic shock due to multiple wasp stings, resulting in cardiac arrest and death. Taking the number of stings (> 100) in one of these cases into account, a differential diagnostic consideration was 'exogenic toxic shock'. Considering the severe reaction with fatal outcome in both patients we cannot rule out the existence of indolent mastocytosis. The third patient developed grade 1 anaphylaxis and severe facial swelling, but survived. In this article we describe the pathophysiological background, treatment, diagnostics and desensitisation therapy.