Ectoparasitism is the most devastating parasitic condition of poultry after coccidiosis. This study was conducted to identify the risk factors associated with avian ectoparasitism in Osun State, Nigeria. Data was obtained from avian species presented at the major Veterinary Hospitals in Osun State between January 2006 and December 2015. A total of 4,584 avian species were presented in the period under review. Of the presented birds, 2,665 (58.14%) were young while 1,919 (41.86%) were adults. One thousand nine hundred and ninety four (43.50%) were male and 2,590 (56.50%) were female. More birds (2,868, 62.57%) were presented during the wet season compared to the dry season (1,716, 37.43%). Turkeys 2,088 (45.55%) were the most frequently presented bird type followed by layers 1,476 (32.20%) and local chickens 1,020 (22.25%). A total of 324 (7.07%) avian species was diagnosed for ectoparasitic infestations of which lice infestation was the most prevalent (216, 4.71%) followed by flea infestation (72, 1.57%), tick infestation (24, 0.52%) and mite infestation (12, 0.26%). There was no defined pattern in the yearly and monthly prevalence of ectoparasite infestations. Age, sex, seasons and species were significantly associated (P<0.05) with the prevalence of ectoparasitic infestations. This study showed a low prevalence of ectoparasite infestations among avian species in the study area; however strategic measures should be taken to control these ectoparasites in Osun State, Nigeria, so as to maximize productivity in the poultry sector
