We studied the ectoparasitics of breeding Lesser Kestrels (Falco naumanni) in Mongolia. We captured 20 adult, one fledgling, and 11 nestling Lesser Kestrels and examined them for ectoparasites in Ikh Nart Nature Reserve, a semi-desert region of Mongolia. We examined 11 nestlings multiple times throughout the nestling period to count carnid flies (Carnus hemapterus). All nestlings age 1–4 d old were infested (mean of 6.0 flies per nestling). Older nestlings had fewer carnid flies over the course of the nesting season. We also collected 120 louse flies (Ornithophila gestroi) from 20 adults and one fledgling, an infestation rate of 85.7%. The mean number of louse flies per host was 6.3 (range = 1–19) per infested bird. These represent the first Mongolian records of O. gestroi and C. hemapterus from adult and nestling Lesser Kestrels. These two fly species have been previously recorded from several diverse avian species in many regions of Eurasia and North America. The paucity of investigations of raptor ectoparasites in Mongolia suggests that this is an important area for future research and that additional reports of other ectoparasites are likely to be forthcoming.