Data on Thelazia californiensis Price, 1930 are presented. The importance of this eye nematode is also related to a few human cases due to this parasite in the USA. This is the first report of T. californiensis occurring in a South American host, Mazama gouazoupira (Fischer, 1814), which is also a new record for the species.
Nematode; Thelazia californiensis; mammal; deer; Brazil