Pentaquine is an 8-aminoquinoline that was used in the 1950s to treat malaria and trypanosomiasis. Pentaquine showed no significant sporontocidal activity against P. gallinaceum in Aedes aegypti. In the experimental animals, the antimalarial effect of pentaquine, its pharmacology and toxicology have been investigated (1, 2). Activity, 80 to 128 times that of quinine and two to eight times that of pamaquin in avian malaria. It has adverse effects very similar to those of primaquine. In mammals it is rapidly absorbed from the gastro-intestinal tract. In acute, and in short term chronic toxicity studies, pentaquine was from one-fourth to one-half as toxic as pamaquin. In the dog, pamaquin in large doses produces severe anorexia, emaciation and ocular paralysis due to central impairment of the sympathetic innervation of the eye. In high dosages pamaquin produces leukopenia, neutropenia, anemia, methemoglobinemia, emaciation, depression, and liver damage in the monkey, effects which are not produced with pentaquine in this species.