Background: Ovine oestrosis is an economically important and widely distributed parasitic disease of sheep that is caused by Oestrus ovis larvae across the world. Despite the fact that Oestrus ovis is a common parasite in Ethiopia and that there are many sheep in the study area, there is no information on the prevalence, larval burden, predilection sites, and risk factors associated with Oestrus ovis infestation in sheep in the Dendi district of West Shewa Zone, Ethiopia. Methods: A cross-sectional study was conducted from November 2017 to April 2018, to estimate the prevalence, risk factors, and larval burden, and identify common predilection sites for Oestrus ovis larvae. A total of 180 sheep heads were randomly selected from five purposely selected restaurants in Ginchi town, Dendi district, transported to the laboratory, opened with a hand saw, and visually examined for infestations. The larvae were collected from positive sheep heads and counted. The sites where the larvae were obtained were recorded. The data were analyzed using SPSS version 20 software. Results: Of the total of 180 examined sheep heads, 104 (57.8%) were infested with larvae of Oestrus ovis. In the study, a statistically significant difference (p > 0.05) was not observed in the prevalence of Oestrus ovis in relation to all considered risk factors such as sex, age, and origin of sheep. From 104 infested sheep, a total of 664 larvae were detected in different parts of sheep heads. The mean larval intensity per infected animal with Oestrus ovis was 6.38. In this study, the minimum and maximum numbers of larvae recovered were 1 and 26, respectively. The nasal cavity, nasal sinus and frontal sinus were the predilection sites of Oestrus ovis larvae identified in this study. Conclusion:Oestrosis is an important and common parasitic disease of sheep in the study area.