Of 317 patients with hypersensitivity to Hymenoptera stings forty had severe local reactions (SLR) only, fifty-nine reported severe local reactions before their first and seven after their last systemic reaction (SR). The probability to develop a life threatening systemic reaction when restung after a severe local reaction was calculated to be about 5%. In 80% of the patients with severe local reactions only, hypersensitivity to either bee or yellow jacket venom could be demonstrated by skin tests and/or RAST. A fair correlation of skin test and RAST results was observed. In patients with severe local reactions hyposensitization therapy with venoms is not generally indicated. In exceptional patients whose allergy is proven by skin tests or RAST and who are at a high risk of being restung, hyposensitization may be considered.