We describe a two year-old multiallergic boy who developed generalized urticaria after the third Di-Te-Pol vaccination. A Type I reaction to the vaccine was demonstrated by performing basophil histamine release to the complete vaccine. Further, we found that the reaction could be exclusively ascribed to Diphtheria-Toxoid whereas no release was observed by the Polio and Tetanus component. The latter result was confirmed since no specific IgE to Tetanus Toxoid could be demonstrated.