The capacity of tegobetain, pyrrolnitrin, tolcyclate and chlorquinaldol to induce delayed-type contact sensitization was studied in guinea pigs in 2 series of tests using the method of Magnusson & Kligman and the authors' modification of the wholly intradermal Draize technique. Histological examination of skin biopsies obtained from the test area demonstrated that tegobetain, pyrrolnitrin and tolcyclate are potential sensitizers.