In order to determine the content of 5-hydroxymethyl-2-furaldehyde (5-HMF) in the Rehmanniae Radix Preparata, 5-HMF was isolated from the EtOAc fraction of the Rehmanniae Radix Preparata samples and identified by spectroscopic and physicochemical evidences. Twenty one samples prepared on the basis of increasing number of stewing times with wine were analyzed by HPLC. From this analysis, it was revealed that the samples processed under one to nine times of stewing showed increasing pattern in 5-HMF contents. And the samples processed under 9 to 18 times of stewing showed 0.53-0.74% in 5-HMF contents. However, for those samples processed more than 19 times, 5-HMF content profile showed decreasing pattern.