Thirty-six 6(7)-substituted-3-methyl- or 3-halogenomethyl-2-phenylthio-phenylsulphonyl-chloro-quinoxaline 1,4-dioxides belonging to series 3-6 were synthesised and submitted to a preliminary in vitro evaluation for antimycobacterial, anticandida and antibacterial activities. Antitubercular screening showed a generally good activity of 3-methyl-2-phenylthioquinoxaline 1,4-dioxides (3d,e,h-j) against Mycobacterium tuberculosis, and exhibited MIC between 0.39 and 0.78 microg mL(-1) (rifampicin MIC=0.25 microg mL(-1)), whereas in compounds 4d,e, 5a,b,d,e,l and 6b-e,j,l MIC ranged between 1.56 and 6.25 microg mL(-1). Results of the antibacterial and anticandida screening showed that 6e and 6l exhibited MIC=0.4 and 1.9 microg mL(-1), respectively, against Candida krusei (miconazole MIC=0.9 microg mL(-1)), and 4i, 5b,d, 6e, MIC=3.9 microg mL(-1) against Candida glabrata (miconazole MIC=0.4 microg mL(-1)), while compounds 3d,l, 5e,l, and 6b,d,e,l showed MIC=15.6 microg mL(-1) against Vibrio alginolyticus.