Sheep are farm animals that have long been cultivated and become abundant food resources for humans. Sheep are particularly susceptible to ectoparasite attacks. One of ectoparasites that could infect sheep is lice, it can reduce the production of meat and decrease quality of leather and fleece. Therefore this research aims to inventory, identify, and study the existence of lice in sheep. Lice samples were collected in four districts in Magetan ie Karas, Parang, Panekan, and Plaosan. Preparations of lice were done by whole-mount with Hoyer's solution. Results showed that species of lice infesting sheep in four districts in Magetan was Damalinia ovis. The prevalence value of D. ovis infested sheep was 100%, it means that all examined sheeps were infested by D. ovis. The largest prevalence value was found on the sheep body (77.86%). The number of individual D. ovis found was not affected by the altitude, air temperature, and humidity.