Ectoparasites were collected from ospreys (Pandion haliaetus) in four study areas within the Great Lakes basin of Ontario, Canada. Two parasitic mite (Acari) species, Bonnetella fusca and Analloptes sp., were collected from nestlings. One chewing louse (Mallophaga) Kurodaia haliaeeti was collected from nestlings and adults. Prevalence and intensity of K. haliaeeti were greater in the most northern of the four study areas. Bonnetella prevalence and intensity did not seem to vary greatly across the study areas. New range and host records are presented for B. fusca and Analloptes sp., respectively.