In the Omiya, Saitama, Abattoir 368, 195 hogs produced within the country were subjected to meat inspection over a three-year period beginning with April, 1963. Of them, forty were found to be parasitized byCysticercus tenuicollis(CT). When these hogs were broken by the region from which they had been shipped, hogs originated from the Tohoku region were ranked first. The highest frequency of occurrence of the groups by age and breed was shown by the group of less than one year and that of the Yorkshire breed, respectively. There was no sex difference in frequency. The infection rate was high in spring and summer, particularly in June, and relatively low in winter. The number of organisms harbored per hog was mostly only one, and 63 at the largest. In most cases, the parasite was found on the capsule of the liver and the omentum majus, but never in the parenchyma of any organ. The cyst was mostly 1-1×4×4 cm in size. The number of hooks ranged from 24 to 38. The large hook was 191-220μand the small hook 131-160μin length. When a dog was infected with five cysts of CT experimentally, four tapeworms were collected from it. Examination of these tapeworms revealed that CT which had been harbored by the hogs was the cyst ofTaenia marginata.