Field trials were carried out to assess the therapeutic effects including the combined use of piperaquine (PQ) with nitroquine (NQ) and pyronaridine (PYR) with NQ against falciparum malaria in regions of Hainan Province with chloroquine-resistance in 3 successive autumns from 1985 to 1987. In an evaluation of PQ 750 mg with NQ 25 mg therapy in 33 falciparum malaria patients, the average fever subsidence time and parasite clearance time were 39 hours and 49 hours respectively, but within 28 days after medication, the recrudescence rates were 0-47% in different regions. In evaluations of PYR 600 mg with NQ 25 mg in 11 cases, PYR 800 mg with NQ 40 mg in 43 cases, PYR 800 mg with NQ 80 mg in 31 cases, the fever subsidence time were 31-35 hours, the parasite clearance time were 46-53 hours and the 28 days recrudescence rates were 13-18%. In the control, the use of PYR 1,200 mg alone in 42 cases, the average fever subsidence time and parasite clearance time were 33 hours and 48 hours respectively, the 28 days recrudescence rate was 12%. There was no statistically significant difference among them in their effects. The side-effects of all groups were mild.