Several measures of immunologic responses of a group of patients with psoriasis were compared to those of a group of control subjects. These included the delayed hypersensitivity reaction to eight intradermally injected antigens, the local inflammatory response as measured by the human skin-window technique, the titers of isohemagglutinins, the titers of Candida agglutinins, and the intensity of the precipitin lines of γ2-, γ1A-, and γ1M-globulins in immunoelectrophoresis. No significant differences were observed between the two groups.