Meat tenderizer containing the proteolytic enzyme papain was tested for therapeutic efficacy in the sting of the imported fire ant. The parameters of pain and itching were used to evaluate qualitatively the sting response in 22 healthy medical students, and the laser Doppler velocimeter was used to assess quantitatively the change in cutaneous blood flow. The results indicated that, during the acute-phase reaction, no clinically or statistically significant difference was found between stings treated with meat tenderizer and stings treated without tenderizer. Therefore we conclude that meat tenderizer is of no therapeutic value in the acute treatment of the imported fire ant sting.