Abstract: A process for utilizing liquefied natural gas as a source of refrigeration in an ethylene plant of the type featuring a "front-end" depropanizer and a forecooling recovery section, wherein the forecooling section is operated at lower than conventional temperature and pressure levels while the final separation section is maintained at conventional operating conditions. Liquefied natural gas is heat exchanged with recovered depropanizer column overhead gas in the forecooling section and with overhead of the demethanizer and C.sub.2 splitter columns to condense reflux, thereby closely matching the cooling curve of the ethylene plant with the LNG warming curve to achieve highly efficient utilization of the LNG refrigeration.