Three hundred thirty-three blue grouse (Dendragapus obscurus) were examined for blood parasites from 11 sites: southern Yukon Territory, southeast coastal Alaska, northern and central interior British Columbia, south coastal British Columbia, northcentral Washington, southcentral Oregon, northwestern California, eastcentral Nevada, northwestern Colorado, and westcentral Montana. Three species of protozoan parasites (Leucocytozoon lovati, Haemoproteus mansoni, Trypanosoma avium) and a splendidofilariid nematode (Microfilaria sp. B) were found in nearly all locations. Prevalence levels were consistently high for L. lovati (92%). The other hematozoa were found less frequently (H. mansoni 29%; T. avium 46%; and microfilaria 29%). The range of these parasites in blue grouse was extended to a more northern (Yukon Territory) and more southern distribution (Nevada) than previously reported. Ranges were also extended to blue grouse populations in Alaska, Washington, Oregon and California.