An incubation study was conducted to know the toxicity level of chlorpyrifos in soil fauna by using earthworm species Eudrillus euginae as a biomarker. The earthworms were incubated in the spiked soils, with concentrations of 200ppm, 100ppm, 50ppm, 25ppm and 10 ppm, for a period of 24 hours. From the study, 100 percent mortality was observed in 200 ppm and 100 ppm. In the case of 50 ppm and 25 ppm, it was 87.5 and 62.5 respectively. The LC50 and LC95 concentrations were calculated from that it was clear that chlorpyrifos is toxic to earthworms.