The compounds being reported in this paper have all been evaluated within the TAACF Antituberculosis Screen Program, and some of them have been shown to possess high growth inhibition activity against Mycobacterium tuberculosis and Mycobacterium avium in the run of the first and second level in vitro screenings. The three compounds which have shown a good SI (Selectivity Index) are 2b, 4b and 4d: in addition,6.7-dimethyl-3-[4-(4′-nitrophenyl)piperazin-1-yl] quinoxaline-2-carbonitrilo 1.4-di-N-oxide (4b) is currently being tested within the in vivo antituberculosis screening in view of its very good in vitro activity.