Abstract: A hot gas defrost refrigeration system has a compressor, a condenser, and an evaporator, interconnected by fluid passage means and incorporating valve means to cause refrigerant to flow sequentially through the compressor, condenser, and evaporator to the compressor during the refrigeration cycle. Refrigerant flow during the defrost cycle is from compressor to evaporator through the condenser to the compressor. The refrigeration system includes defrost passage means, including valve means, connecting the evaporator outlet to the condenser inlet and connecting the condenser outlet to the compressor inlet. A vessel is provided which combines the functions of receiver during refrigeration and superheater during defrost. During refrigeration liquid refrigerant flows from the condenser through the superheater/receiver to the evaporator. During defrost, the defrost passage means directs vaporous refrigerant from the evaporator through the superheater/receiver to the compressor.