Between 13 August and 3 September 1999, 26 green frogs Rana clamitans Rafinesque, 1820, were collected from 2 ponds at the University of Wisconsin-Milwaukee Field Station in Ozaukee County, Wisconsin, U.S.A. Hosts were euthanized and organs were examined for helminth parasites. All host individuals were infected with 1 or more helminth parasites. A total of 11 helminth species infected R. clamitans at this location: 9 platyhelminths (7 trematodes, 2 cestodes) and 2 nematodes. Mean abundance of infection was 65.5 +/- 79.7 worms per host (range = 1-330). This is the first report of Clinostomum sp. from green frogs in Wisconsin.