Gastrointestinal helminths including two species of cestodes (Taenia omissa and T. ovis krabbei) and three species of nematodes (Toxocara cati, Cylicospirura subequalis and Ollulanus tricuspis) are reported from two free-ranging cougars (Felis concolor) in Washington (USA). Ollulanus tricuspis is reported for the first time from cougars and represents the first occurrence of this parasite in a sylvatic felid from North America.