Twelve of 102 woodchucks submitted for necropsy to the New York State College of Veterinary Medicine had clinical histories of central nervous system disorder. All had multifocal eosinophilic encephalitis with formation of granulomas. Nematode larvae, identified as Baylisascaris sp. were found in six of the 12 and were assumed to be the etiologic agent in all affected woodchucks. Both wild and captive (wild-trapped) woodchucks were affected, and all occurrences were between mid-June and early September.