We report a case of air sac nematode (Serratospiculum tendo) infection in an adult male Austral Peregrine Falcon (Falco peregrinus cassini) admitted to a rehabilitation center in Mendoza Province, Argentina, in September 2017. This case of air sac nematodes reported in an Argentine raptor is only the second report of S. tendo in South America. We recommend examination of all raptors, especially those falcon species that include insects in their diet and inhabit open lands and those in rehabilitation centers or kept for falconry, education, or captive breeding. Fecal analysis and microscopic examination of oral swabs for evidence of parasites are simple noninvasive diagnostic procedures that allow easy detection of these parasites under field and captive circumstances.