This article describes a facile one-pot synthesis of different chloro-substituted linear and angular indoloquinolines using iodine as a catalyst and in vitro antiproliferative activity of these chloro-substituted indoloquinolines (3e and 3f) and some indolo[2,3-b]quinolines (3a–d) against human hepatocellular carcinoma HepG2 and human breast carcinoma MCF-7 cells. Anti-proliferative assay against human hepatocellular carcinoma HepG2 and human breast carcinoma MCF-7 cells indicated methyl-substituted 6H-indolo[2,3-b]quinoline 3c to be the most active and the parent 6H-indolo[2,3-b]quinoline 3a to be the least active, while the other compounds including the different chloro derivatives exhibited only intermediate activity.