Abstract: A new antimalarial drug 7351 (pyronaridine or malaridine), 2-methoxy-7-chloro10-3', 5'-his- (pyrrolin-1-yl-methyl)-4'-hydroxyphenylamino-benzo-b- 1,5-naphthy-ridine (Ⅱ_b), was synthesized. Experimental therapy and clinical trials showed that the results are satisfactory. No cross-resistance to chloroquine has been found in animals and in human cases. The drug could be given by oral, intramuscular injection or intravenous drip. It is specific for treatment of severe malaria cases.