After preliminary in vitro screening of 15 newly synthesized compounds belonging to the chemical class of N1-(aryliden)-4-pyridinecarboxyamidrazones against Mycobacterium tuberculosis reference strain H37 Rv, we determined the minimum inhibitory concentrations (MICs) of the six most promising chemicals against different species of Mycobacterium and different strains of M. tuberculosis. The agar dilution method was employed against M. gordonae, M. bovis, M. kansasi, M. avium, M. fortuitum and on eighteen different strains of M. tuberculosis, isolated from human bronchial aspirates. The results obtained confirmed that the newly synthesized chemicals possessed a very interesting antitubercular activity, their MICs ranging from 4 micrograms/ml to 16 micrograms/ml.