To give larger doses of antigen for hyposensitization, yet hold down constitutional reactions and excessive local reactions, the antigen was mixed with epinephrine, ephedrine and dimethpyrindene, the latter a new antihistamine, just before subcutaneous injection. Dimethpyrindene, a potent antihistamine with minimal side effects, was also administered orally. The incidence of constitutional reactions and excessive local reactions was considerably diminished. Larger doses of antigens were tolerated and longer intervals between treatments were possible, a point of particular significance in maintenance therapy. There was less pain and discomfort at the site of injection and clinical results were improved.