We studied skin test reactivity to five commonly used antigens by testing 150 healthy adults. The delayed hypersensitivity (DH) skin test is widely used to assess the immune status of patients. The battery of antigens suitable for use may vary in different countries, but the reactivity to the antigens in our population did not differ remarkably from reports of other authors. The reactivity rates were: candida 32.7%, mumps 86%, streptokinase-streptodornase (SK-SD) 70%, trichophyton 0% and tuberculin 58.7%. Sixteen of the subjects were retested after 2 weeks. Only eight of them showed unchanged reactions to all five antigens. Specific IgG antibody concentrations measured by enzyme-linked immunosorbent assay (ELISA) against each of the five antigens in the serum of 42 subjects before and after testing showed great inter-individual variation. The antibody concentration did not correlate with the DH skin test results, but the testing itself increased the production of anti-mumps- and anti-SK-SD-antibodies.