Abstract: A field trial was undertaken in Jining, Shandong, to evaluate the effectiveness of pirimiphosmethyl in controlling An. sinensis, the main vector of malaria. In one district all human dwelling and animal shelters were sprayed with a dosage of 2g/m2, while in another district only animal shelters were covered with a dosage of 2.25g/m2. The results showed a good effectiveness of the insecticide against An. sinensis. That is, the mosquito density decreased by 90% as compared with that of untreated area, the evening netbait density was much lower within following 5-6 weeks, and the parous rates declined significantly within 3 weeks postspraying. It is concluded that the full coverage spraying showed more effectiveness than the spraying of animal shelters alone.