A female American kestrel (Falco spaverius) fledgling was found on the ground with a suspected trauma to the right eye and open-mouth breathing. During the first 2 days of hospitalization, the bird developed severe bilateral periorbital cellulitis, blepharoedema, and sinusitis. The periocular tissues of the right globe were devitalized and communicated with a fistula at the commissure of the right side of the beak. The blepharoedema of the left eye was aspirated and yielded a dark colored malodorous fluid, which was submitted for aerobic bacterial and Mycoplasma cultures. Results showed a mixed infection with Mycoplasma buteonis, Avibacterium gallinarum, and Staphylococcus pasteuri, all of which are not commonly isolated from birds of prey. With antimicrobial therapy, supportive care, and surgical debridement of the right periocular necrotic tissues and adhesed phthisical globe, the kestrel recovered from this severe mixed upper respiratory infection.