Garter snakes, Thamnophis sirtalis parietalis, that had been fed wild-caught banded killifish, Fundulus diaphanus, and laboratory-bred leopard frogs, Rana pipiens, were infected by larval nematode, Eustrongylides sp; 7 of the 25 snakes died. Signs of infection in 20 snakes included subcutaneous "lumps," violent contortions, and bloody exudate, apparently from the nares. Nemotodes were collected at necropsy from beneath the skin, in the lungs, in the body cavity, and along the spinal column. Nematodes were surgically removed from subcutaneous sites in 2 garter snakes, which recovered completely.