The stools of 697 cases were examined by agar plate technique at Tambon Makam Luang, Sun Pa Tong district, Chiang Mai; there were Strongyloides stercoralis 15.9%,Opisthorchis viverrini 5.1%, intestinal fluke 0.1%. Treatment with ivermectin 78 cases and albendazole 33 cases of strongyloidiasis gave cure rates at 98.7% and 78.7%, respectively. Alkaline phosphatase in some patients were increased at mild level after treatment. Side effects in ivermectin group were anorexia, nausia, diarrhea, diffuse itching and drowsiness; and in albendazole group were nausia and diarrhea. The efficacy of single dose and mild side effects suggest ivermectin as drug of choice for strongyloidiasis treatment.