An antigen capture immunoassay was developed for the detection of mycobacterial antigens in sera from patients with tuberculosis. The assay was evaluated together with an antibody measuring enzyme immunoassay in a clinical trial for serodiagnosis of tuberculosis. Sensitivity of the antibody assay for active pulmonary tuberculosis, including relapsed infections, was 75%, and specificity with other lung diseases was 97%. Sensitivity for extrapulmonary tuberculosis was 84.5% and specificity 84%. Sensitivity of the antigen assay for active tuberculosis was 45% with no false positive reactions. Combination of the results from the two assays increased total sensitivity to 96.5% with a positive predictive value of 0.81 and a negative value of 0.98. The two assay test was relatively simple to perform and offered improved serological diagnosis of tuberculosis over a single antibody test.