Studies on the metabolism of the 8-aminoquinolines, pamaquine, isopentaquine, primaquine, pentaquine, SN 13,058 (2-methoxy-8-(3-diethylamino-propylamino)-quinoline), and CN 1100 (2-methoxy-8-(3-amino-propylamino)-quinoline), were carried out in the rhesus monkey. As shown by differential analyses of the 8-aminoquinoline contents of plasma, each of the above compounds is degraded to alkali-soluble, ethylene-dichloride-insoluble derivatives. This degradation follows either oral or intramusc. admn. of the drugs. The extent of degradation of the different compounds varied markedly, being greatest with CN 1100 and least with SN 13,058. Preliminary studies on CN 1100 showed considerable quantity of the degradation products of this compound in the urine.