In an attempt to synthesize pharmacologically active molecules, we report here the synthesis and in vitro anti-HIV, antimycobacterial and antimicrobial activity of various series of 3-(3-pyridyl)-5-(4-substitutedphenyl)- 4-(N-substituted-1,3-benzothiazol-2-amino)-4H-1,2,4-triazole. The anti-HIV activity of the title compounds was evaluated as selective human immunodeficiency virus type-1 and -2 (HIV-1, HIV-2 RT) inhibitors, antitubercular activity against H37Rv using Lowenstein-Jensen agar method and antimicrobial activity against certain bacterial and fungal strains using the broth microdilution method. The synthesized compounds were characterized by FTIR,1 H-NMR,13C-NMR and mass spectral data together with elemental analysis.