Antimalaria pharmaceutical compositions

Pharmaceutical compositions for preventing and treating malaria are disclosed, said compositions containing naphthoquine phosphate, dihydroartemisinin and trimethoprim or their antimalaria active derivatives, produgs or pharmaceutically acceptable salts. The compositions have a killing plasmodia activity which is significantly higher than each of the three active ingredients or combinations of any two of them, the rate of killing plasmodia increases remarkably without increase in toxicity. The present invention also relates to the use of combinations of the above three active ingredients in preparing antimalaria drugs and a method of treating or preventing malaria by using the above three active ingredients.