The lack of a rapid and reliable method for diagnosis of active tuberculosis necessitated the development of new laboratory techniques. Diagnostic value of a recently developed ELISA for the detection of IgA antibodies to Kp 90 antigen of Mycobacterium tuberculosis was evaluated in this study and the results were compared with the conventional methods and polymerase chain reaction (PCR). Fifty six sera and body fluid (pleural, peritoneal, pericardial) samples from 23 patients with active tuberculosis and 26 control subjects were included in the study. Out of 28 samples obtained from the patients, 22 (79%) yielded positive result for IgA. Comparison ofall positive results implied high level of agreement between IgA measurement and other methods; 9/10 direct examination, 6/7 culture and 18/21 PCR positive samples were found to be IgA positive. Body fluids were as efficient as sera in terms of speciment selection; 14/18 (78%) body fluid samples yielded IgA positivity. LgA detection against Kp 90 antigen by ELISA appears as a rapid and reliable procedure for diagnosis of active tuberculosis. However, evaluation of the test in terms of sensitivity and specificity awaits further studies.