The hypothesis that the introduction of anesthesia in 1846 accelerated the development of surgery was tested by compiling statistics on the types of operations performed in this country and abroad in the absence of anesthesia (prior to 1846) and over the 50-year period after 1846. Prior to 1846, surgery involved the extremities and superficial parts of the body almost exclusively. The same was generally true for 50 years following 1846. The introduction of anesthesia was necessary before surgery could advance, but control of infection, establishment of the sciences of pathology and physiology, and development of professionalism in clinical medicine and surgery based on research and teaching were also required. Almost a half-century lapsed after the introduction of anesthesia before surgery advanced significantly beyond the stage it was at prior to the introduction of anesthesia in 1846.