Abstract: An arm suspension mitt immobilizes and positions a patient's arm for shoulder arthroscopy. The mitt includes outer and inner flexible portions which together define a package having an open end adapted to removably receive a hand inserted into a space radially inward of the inner flexible portion. An inflatable chamber is provided between the outer and inner portions. The inflatable chamber is sealed from the ambient atmosphere. A valve is provided in communication with the inflatable chamber for inflating same thus causing the inner flexible portion to collapse in a direction away from the outer flexible portion so as to conform the inner flexible portion around a hand within the space.