This article is only available in the PDF format. Download the PDF to view the article, as well as its associated figures and tables. Sacral anesthesia was first introduced by Cathelin and was later popularized by Laewin. During recent years, it has come into general use. The terms "caudal" and "epidural" have also been applied to this method of obtaining anesthesia. It consists in the introduction of the anesthetic solution into the lower portion of the bony sacral canal. The fluid disseminates laterally along the course of the spinal nerves, producing conductive anesthesia. The investigations of Thompson in 1917, Brenner in 1923, and others have shown the approximate routes taken by the fluid when injected into the cadaver. Careful checking up of anesthetic areas following the introduction of varying amounts and varying concentrations of procain has been carried out by a number of observers. Harris, Thompson, Kappis and others showed, for instance, that when solutions containing dyes were injected into the sacral canal the nerves in the lower cervical region of the cadaver were