The technique of tail amputation is utilized as a method for interrupting the migration process of Schistosoma mansoni schistosomula from the skin of Fischer rats infected by exposure of the tail to cercariae. The yields of schistosomula recovered from the lungs at different times post-infection are compared, using rats with or without tail amputation. Residence times of schistosomula in skin and lungs, as well as their transit time and efficiency of migration between these sites, are estimated. At least one-third of the infecting cercariae migrate from skin to lung in rats. Amputation of the tail on days 4 or 5 post-infection isolates a definable number of schistosomula in the lung and their migration to the portal circulation can be followed. The kinetics of this migration in rats and mice is compared and a significant difference is revealed.