The aim of this project was to study the population genetics of Echinostoma trivolvis, a parasitic trematode that uses multiple hosts in its lifecycle and has a significant impact on amphibian populations. Microsatellite markers were to be identified and isolated because of their highly variable nature and reported ease of use with PCR. Parasite DNA was extracted from planorbid snails from several locations within California including: Point Reyes National Seashore, Lake Tahoe, and the San Francisco Bay Area. In addition, parasite samples were obtained from Manitoba, Canada. Several microsatellites were identified and 29 PCR primers sets were designed, six of which were capable of amplifying consistently. Sequencing other published molecular markers, COl, NDl, and ITS, unveiled intriguing phylogenetic relationships and potential cryptic species. The echinostome population in central California, as a result of this project, may be much more diverse than has long been reported in the literature.