SITUS inversus, less commonly called transposition of viscera or heterotaxia, has been known from ancient times. Aristotle1 cited 2 cases of transposed organs in animals. Fabricius,2 in 1600 A.D., described a case of transposed liver and spleen in a human being. In 1824, Kuchenmeister,1 first diagnosed situs inversus in a living human being and Vehsemeyer,3 in 1897, demonstrated the condition by roentgen rays. In a review of the literature in 1926, Cleveland4 collected 400 cases up to the end of 1924. Larson,5 in 1938, estimated there had been 75 additional cases reported up to that time. In reviewing the literature from 1925 to 1946, inclusive, I found 632 cases of situs inversus, of which there were 515 examples of dextrocardia, 379 instances of situs inversus totalis, 128 persons in whom dextrocardia was known to be the only form of transposition, 41 cases of partial