Ninety-eight Mexican free-tailed bats, Tadarida brasiliensis mexicana, collected from 4 locations in Mexico between November 1996 and June 1998, were examined for metazoan parasites. Twenty-one parasitic taxa belonging to 3 phyla (Plathyhelminthes, Nematoda, and Arthropoda) were recovered including 5 helminth taxa (3 digenean, 1 cestode, and 1 nematode) and 16 arthropod taxa (12 mite, 2 tick, and 2 insect). The digenean Ochoterenatrema labda was the most prevalent and abundant helminth in collections from the states of Puebla, Zacatecas, and Durango. Urotrema scabridum and Dicrocoelium rileyi reached the highest values of prevalence and mean abundance of infection in Nuevo León state. Among arthropod taxa recovered, Chiroptonyssus robustipes was the most prevalent and abundant parasite in all 4 localities, and its nymphal stage was the most abundant form recovered. In total, 10 new host and 43 locality records are presented.