Slaughterhouse surveys to determine the prevalence and intensity of larval Oestrus ovis Linnaeus (Diptera: Oestridae) in sheep, were conducted monthly for 1 year in Konya, Turkey. A total of 624 sheep, selected at random, were examined and 59% were found to be infested by O. ovis. A total of 8801 larvae were collected, of which 68.9% were first-stage, 19.1% second-stage and 12% third-stage larvae. All three larval stadia were seen in each month of the year. The larval intensity for infected sheep was 23.9, with 16.48 L1, 4.55 L2 and 2.87 L3. The monthly prevalence ranged from 34.6% in January to 76.9% in October. The largest number of larvae (180) was obtained from a sheep in August (122 L1, 52 L2 and 6 L3). The infestation rate was higher in 4-6-year-old sheep, at 72.6%. The infestation rates were 64.4% in female and 47.5% in male sheep. © 2006 The Royal Entomological Society.