Synthesis of new chiral thiourea derivatives (27 examples) as anticancer agents has been described. Three compound 7d (NSC code 761448/1), 7e1 (NSC code 767161/1), and 7e3 (NSC code 767160/1) were found to exhibit higher anticancer activity than 5-fluorouracil against Colon cancer, Melanoma, Ovarian cancer, and Breast cancer subpanels. The effect of stereochemistry of amino acid residues on the tumor growth inhibitory activity has also been studied. Keywords: Amino acid residues, anticancer therapy, thiourea derivatives.