This monograph is based almost entirely upon the files of the War Department, supplemented in some instances by information obtained orally from certain individuals with special knowledge of the Army hospital ships. In particular, considerable assistance was derived from the staff and records of the Water Division, Office of the Chief of Transportation, Army Service Forces. In addition, the Medical Regulating Officer, Office of the Surgeon General, Army Service Forces, placed his inactive files at the disposal of the writer. At present, five additional vessels have been selected for conversion into Army hospital ships. The conversion program, as extended, will not be accomplished until the spring or early summer of 1945, but represents no radical departure from the procedure already developed. Accordingly, it has appeared advisable to close the account at this point, since further developments may be incorporated in an addendum of a later date. The evacuation of the sick and wounded is a perennial problem in the history of warfare. The initial phase of such evacuation, namely, the assembling of patients from the battlefield, has long been and still is the task of the litter bearers. To carry on beyond the preliminary phase of collecting the sick and the wounded, the United States Army, in common with other armies, has resorted to various forms of transport ranging from animal and motor-drawn ambulances to hospital trains, vessels, and airplanes-all designed to bring the patients to a place where they can receive adequate medical attention. The purpose of this brief account is to describe the complex process of evacuation solely as it involves water transportation and, more particularly, the use during the current conflict of Army hospital ships enjoying a protected status under international agreements. Important though their role is, it should be understood at the outset that Army hospital ships return to the United States only a small portion of the sick and wounded of the armed forces. Practically every returning Army transport carries patients; and the Air Transport Command, Army Air Forces, brings back the sick and wounded regularly by airplane. Moreover, in addition to its own fleet of convention-protected hospital ships, the Navy utilizes hospital spaces on its own transports for the evacuation of patients by water. For evacuation by air the Navy relies upon the Naval Air Transportation Service.