SUMMARYPatients withTrichophyton mentagrophytesandT. rubruminfections were compared in terms of cutaneous responses andin vitrolymphocyte reactivity to trichophytin and other antigens. Twelve out of fourteenT. mentagrophytespatients exhibited delayed cutaneous hypersensitivity to trichophytin. MostT. rubrumpatients (thirty‐seven out of forty‐nine) lacked delayed reactions to trichophytin specifically, but these patients frequently manifested immediate weal reactions to this antigen. Positive lymphocyte responses correlated with the presence of delayed but not immediate cutaneous reactions. Serum from chronicT. rubrumpatients failed to inhibit lymphocyte responses. Possible mechanisms for selective anergy in chronicT. rubrumpatients are discus