An LNG sampling system is provided which includes a sampling probe. The sampling probe includes a backflow prevention check valve positioned within the probe adjacent the inlet end. The probe is inserted into a source of LNG to extract samples of LNG by providing a pressure differential between the probe piping system and the pressure of the LNG within the source. In the event the pressure in the piping system increases above a predetermined amount, the check valve will close preventing backflow of LNG from the sampling system back into the source.