Platelet crystals of linear polyethylene recrystallize extremely rapidly when immersed in a bath of a hot liquid such as ethylene glycol, glycerine, or Woods metal. This recrystallization rate is much faster and to greater extent than when the heating medium is air. For example, heating in the liquids at 127°C causes the length of the chains between folds to increase 50% in 1 sec; the ultimate increase of 200% occurs in about 10 sec. No definite explanation is presently apparent for this much faster rate and greater extent in liquids. No evidence is found for reversibility when annealed crystals are reheated at a lower temperature.