Abstract: A hot gas defrost type refrigeration system in which refrigerant used to defrost is returned to the system's refrigerant circuit after being collected and reduced in pressure, as by expansion valve means, to a pressure below the pressure in the system's return suction header, then heated as by means involving heat exchange with the system's high pressure refrigerant, the refrigerant used to defrost thus being in a superheated gaseous state and returned to the system's return suction header in such state without risk of introduction of liquid refrigerant to the system's compressor(s).