Chlordane is widely used as an anti-termite pesticide for wooden houses. Pest control operators as well as the residents of chlordane treated houses might become sick through the exposure to the chemical. The chlordane concentration in the air and soil after the treatment was examined. The Chlordane concentration in the blood of pest control operators was also examined. A 40% emulsion of chlordane was used together wigh a 2% pestrolum emulsion as a sprinkling pesticide. Its constituents as determined by GC-ECD were in the descending order of trans-chloirdane, trans-nonachlor, cis-chlordane, γ-chlordene, heptachlor and cis-nonachlor. The Chlordane concentration in the air was the highest immediately after the treatment, and decreased gradually with the lapse of time. Heptachlor was the largest, and cis-nonachlor the smallest constituent of chlordane detected in the air. On the contrary, cis-nonachlor was the largest, and heptachlor the smallest contituent in the soil. This suggests that the exposure dose of heptachlor may be extreme. Heptachlorepoxide and oxychlordane as metabolites, and trans-nonachlor and cis-nonachlor were detected in the blood of pest control operators. The C.P.K. value increased in their blood.