We report synthesis and anti-tuberculosis activities of a series of novel ring-substituted quinolines. The most effective compound of the series 3d (MIC = 6.25 mug/mL, Mycobacterium tuberculosis H37 Rv strain) was synthesized in one step; thus is an attractive lead molecule for anti-tuberculosis drug development. The results of this study represent the discovery of ring-substituted 4-methylquinolines as new class of potential anti-tuberculosis agents. (C) 2003 Elsevier Science Ltd. All rights reserved.