Following closely upon the controversial introduction of the Neurocalometer in 1924, the announcement of the Hole-In-One (HIO) theory created yet another significant stir in the chiropractic profession in the early 1930s. Surprisingly, no one has ever tried to trace the history of HIO using primary reference material. Today, numerous spin-off techniques from HIO exist. Some claim that B.J. Palmer invented HIO while others say it was Aleck August Wernsing, D.C., from California. Was it really B.J. Palmer's idea, or did he get it from Wernsing? In this paper the authors have attempted to trace the origins of HIO theory.