A method for detection of mycobacterium tuberculosis antigens in biological fluids provides immunoassay methods, diagnostic kits, and an immunochromatoraphic assay device for detection of Mycobacterium tuberculosis antigens in biological specimens, preferably body fluids and tissues. The preferred body fluids are blood, serum, plasma, urine, pulmonary fluid, sputum, cerebrospinal fluid, and the preferred tissue is the lung biopsy specimen. The immunoassays require two primary antibodies against RD1, RD2, or RD3 of Mycobacterium tuberculosis. At least one of the primary antibodies is attached to a solid carrier. Optional, a second antibody against an animal species producing one of the primary antibodies can be added. Either the other primary antibody or the secondary antibody is labeled with a detection agent, which can be an enzymatic marker, a fluorescent or luminescent agent, a radio active label or a color particle. The biological specimens may be used directly, concentrated or diluted for the immunoassays.