A series of quinazoline-2,4,6-triamine (quinazoline) and 2,6-diaminoquinazolin-4(3H)-one (quinazolinone) derivatives were designed, synthesized and evaluated as cytotoxic agents in three cancer cell lines (HCT-15, SKOV-3, and MDA-MB-231) using conventional MTT assay. Of the tested compounds, only eleven quinazoline derivatives showed activity against all the tested cell lines, at 24 h of exposure. Among them, the compounds 3e and 3f exhibited the highest cytotoxic activity, with the most important IC 50 values ranging from 4.5 to 15.5 μM. They were more active than the reference drugs (Gefitinib, PD153035) which showed IC 50 values ranging between 19.4 and 48.8 μM. These compounds open new possibilities for preparing novel analogous of quinazoline as antitumor agents.