The study concerns 264 cases among which: 119 active lung tb. eliminating and 11 cases not-eliminating M. Tuberculosis; 17 cases of extrarespiratory tb. confirmed by bacteriology and/or by anatomopathology; 18 cases of bone-joint non-tb disease; 38 cases of chronic lung disease other than tb; 61 healthy persons (controls). Sera from these cases were collected before treatment and submitted concomitantly to two different methods: (1) Mycodot test (immunoblot) with lipoarabinomannan (LAM) as antigen, on nitrocellulose discs (Dynagen, Cambridge, MA, USA); (2) ELISA test with antigen 60 (A60) (ANDA-Biologicals, Strasbourg, France) and with antigen I.C. (Cantacuzino Institute, Bucharest). The results were estimated on terms of sensitivity and specificity. As for sensitivity the results show 74-90%. the highest values were reached in ELISA with A60 IgA. The specificity of the Mycodot test was highest: 90-100% in the two successive experiments. The active tb diagnosis discrimination capacity of the studied methods allows the following classification: 1. Mycodot test with LAM antigen 2. ELISA with A60-Ig G complex 3. ELISA with I.C. antigen The Mycodot test is more advantageous being more rapid and more simple to perform.