A program of annual booster injections of mixed stinging insect whole body extract was given to 133 patients who had previously had three years or more of immunological treatment for systemic reactions of Hymenoptera stings. Two patients who were restung had mild symptoms that were evidenced by a few scattering hives with itching. No patient on a dose of 0.2 ml of 1:10 dilution extract had any reaction when they were restung. It is believed, therefore, that this program merits continuation with that dosage for a period long enough to determine its true effectiveness. There is some indication that this is an improvement over the program which stops treatment after three years. There is further support for the belief that this condition and the treatment are dose related. There is also evidence for my belief that this sensitivity, and the treatment, differ from the usual atopic sensitivity in antibody-antigen response.