A series of 4-alkyl/aryl-2,4-dihydro-5-((6-(4-bromophenyl)imidazo[2,1-b]thiazol-3-yl)methyl)-3H-1,2,4-triazole-3-thiones (3a-i) and 2-alkyl/arylamino-5-((6-(4-bromophenyl)imidazo[2,1-b]thiazol-3-yl) methyl)-1,3,4-thiadiazoles (4a-c) were synthesized starting from 6-(4-bromophenyl)imidazo [2,1-b]thiazole-3-acetic acid hydrazide. The newly synthesized compounds were characterized by IR, (1)H NMR, mass and elemental analysis. All compounds were tested for antibacterial and antifungal activities. The antimicrobial activities of the compounds were assessed by the microbroth dilution technique. The compounds were also evaluated for antituberculosis activity against Mycobacterium tuberculosis H(37)Rv (ATCC 27294). The preliminary results revealed that some of the compounds exhibited promising antimicrobial activities. (C) 2009 Elsevier Masson SAS. All rights reserved.