A series of 5- or 7-substituted 3-{4-(5-mercapto-1,3,4-oxadiazol-2-yl)phenylimino}-indolin-2-one derivatives were synthesized by treating 5-(4-aminophenyl)-1,3,4-oxadiazole-2-thiol with different isatin derivatives. The newly synthesized compounds were characterized on the basis of spectral (FT-IR, (1)H NMR, MS) analyses. All the synthesized derivatives were screened for anticancer activity against HeLa cancer cell lines using MTT assay. All the synthetic compounds produced a dose dependant inhibition of growth of the cells. The IC50 values of all the synthetic test compounds were found between 10.64 and 33.62 μM. The potency (IC50 values) of anticancer activity of compounds VIb-d was comparable with that of known anticancer agent, Cisplatin. Among the synthesized 2-indolinones, compounds VIb-d with halogen atom (electron withdrawing groups) at C5 position showed the most potent activity. These results indicate that C5 substituted derivatives may be useful leads for anticancer drug development in the future.