ExtractFew mental diseases have attracted the attention of medical men working in outlandish parts of the world more than Latah. This is due, not only to its intrinsic interest, showing as it regularly does the unusual symptoms of echolalia, echopraxia, and automatic obedience, but also to its remarkable geographical distribution. This illness was described by travellers to the Malay Archipelago in the latter part of the nineteenth century, but very similar reactions were later found to exist in other lands, known to the native peoples by other names. The term “Latah,” however, is the best known, and as the common features between these various reactions became apparent, it has been used as an inclusive name for them all. It is to-day employed with much the same connotation in the French, Dutch, Italian, and English literature, but the discussion of its nature betrays inadequate understanding, attempts at its nosological classification remain unsatisfactory, and speculations as to its aetology continue to be somewhat fanciful.