The use of in vitro release of interferon-gamma (IFN-gamma) in the diagnosis of contact allergy to potassium dichromate was studied in 20 patients who had positive patch tests to chromate and in 30 control subjects (10 patients with contact dermatitis, allergic to other allergens, 10 patients with other dermatologic diseases and 10 healthy subjects). The release of IFN-gamma in the supernatants of the peripheral blood lymphocytes was significantly higher in the patients with proven allergy to chromate (P = 0.001). Further studies are needed to determine if IFN-gamma release may serve as an additional diagnostic tool in contact dermatitis.