Isatins (3a-j) were prepared by using Sandmeyer method and 5-amino-1, 3, 4-thiadiazole-2-thiol (4) was obtained by reacting thiosemicarbazide and carbon disulphide. Schiff bases (5a-j) were prepared by stirring isatins (3a-j) with 5-amino-1, 3, 4-thiadiazole-2-thiol (4). The structures of synthesized compounds were confirmed by analytical (C, H, N) and spectral (FT-IR, 1H NMR, 13C NMR and Mass) data. All the synthesized compounds were screened for in vitro antimicrobial activity by agar well diffusion method and for in vitro antitubercular activity by BACTEC radiometric method using M. tuberculosis H37Rv. All the synthesized compounds 5a-j showed better antibacterial and antifungal activity compared to reference standards ciprofloxacin and fluconazole respectively. Compound 5d exhibited equipotent antitubercular activity compared to the reference standard streptomycin.