The Africanized honeybee, popularly known as the "killer bee," is already well established in Texas and has recently entered California and Arizona. As the Africanized honeybee spreads in North America, the medical community must become aware of the problems associated with this insect and ensure that sting emergencies can be handled quickly and appropriately. The major differences between Africanized and European honeybees are that the former are more irritable, they swarm more readily and frequently, they defend their hives more vehemently, and they sting more collectively. It is not the composition nor the volume of an individual bee's venom, but rather the cumulative dose of multiple stings that accounts for the morbidity and mortality associated with Africanized honeybee-sting incidents. Even nonallergic persons are susceptible to the toxic effects of these large combined venom loads. Africanized honeybee-sting victims are treated the same as victims of European honeybee stings. Authorities will prepare for the bees' arrival by expanding public awareness, teaching risk-avoidance behavior, providing for the removal of troublesome hives, and developing sting treatment protocols that can be initiated rapidly in the field or emergency departments. Health care professionals should participate in the educational efforts and in the development of needed emergency response protocols so that the effects of the Africanized honeybee will be merely a nuisance rather than a plague.