The ability of region of deletion-1 (RD-1)-encoded culture filtrate protein-10 (CFP-10) to supplement the sensitivity of 38-kDa antigen was studied using enzyme-linked immunosorbent assay in pulmonary tuberculosis (TB) patients and controls. The sensitivities for individual antigens ranged from 50% to 60%, and the specificity was 100% for immunoglobulin (Ig) G alone. When IgA results were added to IgG, the sensitivity increased. On combination of the isotype results, sensitivity increased to 61.8% and 57.2% (for 38-kDa antigen and CFP-10), respectively, and specificity changed to 98.8% and 99.4% for 38-kDa and CFP-10, respectively. Combination of results of both the antigens gave 82.4% sensitivity in smear-positive and culture-positive group, and 98.1% specificity. In smear-negative and culture-positive group, the sensitivity was 66.7%. In smear-negative and culture-negative cases, a sensitivity of 65.6% was obtained. This study demonstrates that the use of RD-1-encoded CFP-10 enhances the sensitivity of 38-kDa antigen and can be a useful diagnostic marker in TB.