Allergic contact dermatitis from moderate and weak contact sensitizers is generally studied with guinea pigs, since they are readily sensitized to contact allergens. Mice, by contrast, are poor responders to weak contact allergens. However, the variety of in vitro murine systems us well, is murine specific reagents make mice the preferable species, with the use of vitamin A supplementation, 2 protocols were developed which sensitized CBA/J female mice to paraphenylenediamine, Mice were sensitized by 5 daily topical applications to shasen dorsal skin. Alternately mice were sensitized by 2 intraperitoneal infections of antigen pulsed spleen cells. Sensitization to paraphenylenediamine was determined by ear swelling following topical application. Vitamin A supplementation was found to be essential for optimum response. Lymph node and spleen cell from sensitized mice were capable of proliferating to paraphenylenediamine in vitro. With the use of Vitamin A supplementation and intraperitoneal injection, CBA/J mice were also sensitized to a number of compounds structurally related to paraphenylenediamine, including the ortho- and meta-derivatives of paraphenylenediamine, as well as hydroquinone and resorcinol. These new protocols, combined with vitamin A supplementation, expand the use of mice to study moderate sensitizers with minimal animal utilization.