A new series of substituted benzylamino- and heterocyclylmethylamino carbodithioate derivatives of 4-(3H)-quinazolinone were synthesized via four steps starting from 2-amino-5-methylbenzoic acid and initially screened against A-549 (human non-small cell lung cancer), HCT-8 (human colon cancer), and Bel-7402 (human liver cancer) cell lines at the single concentration of 5 microg/mL using the colorimetric MTT assay. The IC50 values were determined for the compounds reaching > or = 70% inhibition in primary screening by serial dilution. Among the newly synthesized compounds, 9n exhibited potent in vitro cytotoxicity against A-549, HCT-8, and Bel-7402 cell lines with the IC50 values of 1.65, 0.93, and 1.43 microM, respectively.