A new series of piperazine-1-carbodithioate derivatives of 2-substituted quinazolin-4(3H)-ones were synthesized via a five-steps procedure starting from 2-amino-5-methylbenzoic acid. The cytotoxicity of the resulting compounds against A-549 (human lung cancer), HCT-8 (human colon cancer), HepG2 (human liver cancer), and K562 (human myelogenous leukaemia) cell lines was determined by the MTT assay. Preliminary screening results of these compounds are reported.