In the life cycle of Cephalogonimus americanus Stafford, 1902, frogs are infected by ingesting tadpoles containing metacercariae. The author suggested that metacercariae around the mouth of a tadpole might reach the intestine during metamorphosis and develop to adults of C. americanus in the frog. Further studies have not confirmed this idea. Frogs and tadpoles used in these studies came from an acid bog where snails have not been reported. Six Rana clamitans Latreille tadpoles with well-developed hind legs and evidence of foreleg development were exposed to large numbers of C. americanus cercariae. Later, two of these tadpoles were examined and approximately 250 metacercariae were recovered from each tadpole and were present around the mouth, in the visceral organs, and in the lining of the intestine. The remaining tadpoles completed metamorphosis 18 days after infection and were necropsied 15 days after metamorphosis. None harbored C. americanus in the intestine. It was found that cercariae readily penetrated into the epidermis of frogs. Metacercariae encysted in the epidermis and none were found in the underlying muscles as determined by skinning and examining the epidermis and muscles of two frogs 30 min after the termination of exposure. The internal organs of these frogs were not examined. Of four frogs exposed to cercariae one examined 10 days after exposure had 7x immature C. americanus and one examined 15 days after exposure had 15 worms. Two frogs examined 25 and 40 days after exposure had 15 and 22 worms, respectively. Some were clustered near the common bile and pancreatic opening; none contained eggs. Apparently frogs can become infected when they ingest their shed skin that contains metacercariae. This does not rule out the possibility that cercariae penetrate into the body cavity, ultimately to encyst in the intestinal lining where they would have access to the lumen of the intestine.