Abstract: Groups of mice were administered intragastrically either with primaquine alone or in combination with pyronaridine. The number of mice died in groups treated by pyronaridine 293-507 mg/kg combined with primaquine 50 mg/kg were not more than those in group by primaquine alone, but significantly less than those in groups by combination of chloroquine 102-253 mg/kg and primaquine. The tests of primary tissue schizontocidal activity in rhesus monkeys inoculated, with Pladmodium cynomolgi sporozoitcs showed that all monkeys were cured either by treatment of ig primaquine alone, 3 mg/kg/d × 3, or by a single im dose of pyronaridine 10 mg/kg combined with primaquine starting on the day of infection. No influence of pyronaridine on primaquine was observed in P. yoelii sporozoites-infected mice.