The aim of this study was to determine the reliability of skin tests with common antigens as a measure of delayed-type hypersensitivity response in children undergoing tuberculin skin test (TST). Children from developing countries underwent TST as well as skin tests with diphtheria-tetanus vaccine (DT) and candida antigens prior to heart surgery. We included 52 children (mean age: 7.16 years). Forty-two (81%) and 20 of the 52 patients (38%) reacted to the DT and candida skin tests, respectively (P < 0.001 for the difference in response to these antigens). There was no difference in response to candida and DT antigens between patients with positive or negative TST. There was no difference between patients aged 6 years or older compared to younger patients in the response to DT or candida antigen. Skin tests with common antigens are associated with a high false-negative rate and may not predict reliably a state of anergy.