A positioning system for a body comprises a flexible bag of a gas-impermeable material/including a valve to permit evacuation of the interior thereof, the bag containing a flowable granular material and at least one bolster. The body can be at least part of a human form, such as a patient. Systems are generally provided for specific body regions such as the hip or thorax, and for the whole body. The bolster is larger than the grains of the granular material. A size dimension of the bolster is therefore preferably at least 5 times the- size dimension of the granular material, although it sill usually be one or more orders of magnitude larger. Various forms of bolster are possible. A bolster that includes a generally flat section and an upstanding section extending therefrom can be used to locate a shoulder region of the patient in a reproducible yet comfortable form. A bolster that is generally cylindrical in shape can be used to support various areas of a patient such as the neck or knee. The granular material can consist of polystyrene spheres. The bag is preferably of a nylon material; such as a nylon material coated with a polyurethane-based coating.