Stings by the imported fire ant almost always lead to dermal wheal and flare reactions followed by sterile pustules at sting sites. Less commonly, large local dermal reactions, pyoderma, anaphylaxis, or neuropathy may occur. Such reactions have previously been associated with contact with the insects out of doors. We present two previously unreported cases of indoor attacks on individuals by imported fire ants. One patient experienced a cerebrovascular accident in association with the attack, whereas the second patient had no obvious sequelae. With those two reports, a total of four such indoor massive sting episodes have appeared in the recent medical literature. Physicians and other individuals living in areas indigenous to the fire ant should be aware that infestation of buildings with fire ants may be associated with attacks on human beings indoors. Individuals with cognitive dysfunction seem to be especially at risk for attacks by fire ants.