Lungworm prevalence and intensity in pronghorn antelope (Antilocapra americana) were studied from the National Bison Range (NBR) and Yellowstone National Park (YNP). Collections were made from August, 1965 to July, 1966. Protostrongylus macrotis was recovered from 97 of 99 (96.9%) YNP pronghorns, with a mean intensity of 22.1 (0- 133) worms. Protostrongylus macrotis was found in pronghorns of all ages and was present during all months of the year. Lungworms were not recovered from 26 NBR pronghorns sampled during the same time period.
