A living terrestrial planarian, Bipalium fuscatum, was coughed up by a child in Chiba Prefecture, Japan. Severe coughing and respiratory difficulties during the preceding 4 days suggest the worm had been present in the respiratory tract for that period. A related species, B. venosum, had previously been reported by a Japanese physician in Kyushu to have been passed during defecation by a woman hospitalized for rectal bleeding. No explanation is available as to how the worms were acquired. In Atlanta, Georgia, a B. kewense was encountered in the diaper of an infant, which appeared to have been passed with the stool. These cases suggest that these free-living flatworms will invade body openings and can survive for some days as pseudoparasites. Standard texts on parasitology treat only two of the classes of the Phylum Platyhelminthes, the Trematoda and Cestoda. The third class, the Turbellaria, comprising primarily free-living forms, has been almost entirely ignored by medical parasitologists and physicians. The terrestrial turbellarians are nocturnal predators in humid environments. This report describes our experiences, and that of a colleague in Kyushu, Japan, which have led us to believe that several species of one widely distributed genus of terrestrial planarians can be pseudoparasites and possibly produce lesions in