Blood films from 361 sage grouse (Centrocercus urophasianus) from North Park, Colorado, were examined for hematozoa. Parasites found were: Plasmodium pedioecetii, Haemoproteus canachites, Leucocytozoon bonasae, Trypanosoma avium, and microfilariae. The sage grouse represents a new host record for Plasmodium. Prevalence of parasitism was not age or sex related, with no significant (P > 0.05) differences between age or sex class. Parasite burdens increased significantly (P < 0.05) from January through May. As these burdens rose prior to the emergence of potential vectors, probably it was a true relapse associated with the resumption of the hosts' sexual activity.