Twenty-six drugs were applied to DLST. The median interval between first and second DLST was 82 (27-247) days. In second DLST, three drugs (11.5%) turned to be positive, and stimulation index (S.I.) markedly increased in six drugs (23%). On the other hand, S.I. decreased in eight drugs (30.7%). The first DLST demonstrated sensitivity 53.9%, specificity 58.3%, positive predictive value (PPV) 58.3%, and negative predictive value (NPV) 57.1%. The second DLST demonstrated sensitivity 87.5%, specificity 72.2%, PPV 58.3%, and NPV 92.9%. The second DLST improved sensitivity, specificity and NPV.