A 5-year-old boy was evaluated for a history of an anaphylactic reaction to a DPT immunization at 18 months of age. Cutaneous tests and RAST disclosed high titers of IgE antibody to tetanus toxoid vaccine. Variable sensitivity to different vaccine commercial preparations was demonstrated. Immunization was achieved using a 9-step graded dosing schedule with the tetanus toxoid vaccine to which the patient was least sensitive.