The Morton ether inhaler in the possession of Massachusetts General Hospital, Boston, MA, was traced back to 1906 when the earliest known photograph of it was published. The authors believe that the inhaler was given by William T. G. Morton, MD, to J. Mason Warren, MD, in January 1847. The inhaler was acquired by the Warren Anatomical Museum at an unknown date, loaned to Massachusetts General Hospital in October 1946, and placed on permanent loan to Massachusetts General Hospital in April 1948. Many documents relating to the inhaler have disappeared, and it was only identified in 2009 as the inhaler that probably belonged to J. Mason Warren, MD. The inhaler is not believed to be the one that Morton used on October 16, 1846, at Massachusetts General Hospital. It is the only known example of a Morton ether inhaler with valves (excluding replicas or reproduction inhalers) and is probably of similar design to the inhaler that Morton used on October 16, 1846.