A series of bithienyl-pyrimidines having cationic side chain have been developed as antitumor agents. This work illustrates the overwhelming importance of the bithienyl unit for efficient DNA binding. The X-ray structure of 4-(2′, 2 ″-thien-5-yl)-2-chloropyrimidine was obtained for postulating the conformation of the bithienyl-pyrimidine moiety.