The prairie rattlesnake (Crotalus viridis viridis) was experimentally infected with tetrathyridia of Mesocestoides sp. Individual snakes were killed at 4 wk increments, and sections of the stomach, small intestine, large intestine and attached mesenteries were examined for nonencapsulated and encapsulated tetrathyridia. Capsule formation was asynchronous with 9 to 80% encapsulated metacestodes. The distribution of tetrathyridia in the wall of all segments of the gastrointestinal tract is presented as evidence that this metacestode is principally a tissue dwelling parasite.