SummaryThe cutaneous reactivity to tuberculin and DNCB, the in vitro lvmphocyte transformation to phytohaemagglutinin, and serum immunoglobulin concentrations were studied in 36 sarcoid patients and 50 controls.The data show a decreased skin reactivity to the antigens us:d. When compared to an age matched control group, there was only a significant difference for the reactivity to PPD. Tuberculin anergy was most pronounced in patients with pulmonary infiltrates and hilar lymphadenopathy (clinical stage II) suggesting that cutaneous reactivity is more depressed in patients with a more active stage of the disease. In vitro lymphocyte transformation was decreased in sarcoid patients but this was not statistically significant. An increase in IgA and IgG level was noted in sarcoid patients but was not statistically significant when compared to the age matched control.