A total of 35 adult Eastern gray treefrogs, Hyla versicolor LeConte, 1825, was collected in May 2015 from 1 pond in the Kellogg Biological Station Lux Arbor Reserve in the lower Peninsula of southwestern Michigan, U.S.A., and examined for helminths. Three helminth species (1 Monogenea, Polystoma nearcticum; 1 Digenea, Clinostomum sp.; and 1 Nematoda, Cosmocercoides variabilis) were found in adult treefrogs. Polystoma nearcticum is reported for the first time in Michigan and had the highest prevalence (54%), with a mean intensity of 2.4. Cosmocercoides variabilis had the highest mean intensity (52.6) and the second highest prevalence (40%). Clinostomum sp. infected only 1 frog. Twenty-nine tadpoles of gray treefrogs were collected in June 2015 from the same pond that adults were collected from and examined for helminths. One branchial form of P. nearcticum was found on the gill of 1 tadpole. The nematode Gyrinicola batrachiensis infected 55% of the tadpoles with a mean intensity of 2.8. This study is the first survey of the parasites of Eastern gray treefrogs in Michigan.