We present the first prevalence data of hepatic capillariasis in muskrats in Pennsylvania and Connecticut (USA). The prevalence of hepatic capillariasis in five groups of muskrats coming from different locations and numbering 81, 229, 11, 19, and 20 animals, was 42%, 78%, 36%, 16%, and 0%, respectively. Liver lesions varied from minimal to severe multifocal granulomatous hepatitis, often containing adult worms or eggs.