Abstract: A method for liquefying natural gas comprises heat exchanging a pressurized natural gas with two independent coolant circuits. The first coolant circuit pre-cools the compressed natural gas. After the natural gas is pre-cooled in the first circuit, a major portion is liquefied in heat exchange with the coolant in the second circuit while the remaining minor portion is liquefied in heat exchange with the flash gas formed when the so liquefied natural gas is expanded. Subsequent to the flash gas being heat exchanged with the divided minor fraction of natural gas, it is compressed and then at least partly liquefied in heat exchange with the coolants in the first and second circuits and subsequently expanded in the separator containing said flash gas.