Abstract: A method of applying therapeutic heat, and a heat pack for providing therapeutic heat-transfer, are simple, inexpensive to use and practice, and readily re-usable. A piece of polyurethane foam wrapped by an absorbent material such as terry cloth or cotton batting, is saturated with water, placed in an inner nylon bag, and disposed in an envelope made of foam-lined flocked fabric, to form the pack. The pack is placed in a microwave oven to heat the water, and when removed is placed on a body part to be treated. The pack may be reheated and re-used, without opening, repeatedly. The outer covering is longer than the inner core, and can be folded-over to provide several thicknesses of insulation on one face of the pack, while the other face has a single thickness.