Aim: To investigate the quinoline alkaloids from the roots of Dictamnus angustifolius G.Don ex Sweet (Rutaceae). Method: The quinoline alkaloids were isolated by various column chromatographic methods and their structures were elucidated on the basis of spectral analysis. Results: A new quinoline alkaloid, 5-methoxylrobustine (1), along with five known quinoline alkaloids were obtained, and their structures were identified as dictamnine (2), robustine (3), isopteleine (4), γ-fagarine (5), and skimmianine (6). Cytotoxicity testing of these alkaloids showed that all of them had weak cytotoxic activities against human breast cancer cells (MCF7). Conclusion: Compound 1 is a new quinoline alkaloid. Alkaloid 3 showed stronger anti-proliferation effect than the other alkaloids. © 2014 China Pharmaceutical University.