A series of 5-chloro-1H-indole-2,3-dione 3-thiosemicarbazones 3a-g were synthesized to investigate the chemotherapeutic activities. The structures of 3a-g were confirmed by the spectral data (IR, H-1 NMR, C-13 NMR-APT, C-13 NMR-DEPT, HSQC, HMBC) and elemental analysis. Anticancer activities of the compounds were evaluated using cell kinetic parameters on HeLa cells derived from human cervix carcinoma. The preliminary screening results indicated that alkyl substituted compounds 3a, 3b and 3d were more effective in mitosis phase when compared to the synthesis phase. 3a-g were tested against some DNA and RNA viruses in CRFK, HeLa, HEL, MDCK and Vero cells. None of the compounds was active against any of the RNA or DNA viruses at 100 mu M. All compounds were also evaluated for antimicrobial activity against selected strains. Methyl substituted 3a and allyl substituted 3c were found to be active against S. aureus and C. albicans.