A new method of gibberellin A3 detection based on high-performance liquid chromatography has been elaborated. It combines high accuracy and low cost, and includes the following stages: fixation with liquid nitrogen; extraction of alcohol-soluble substances; purification with freezing, reextraction in ethyl acetate, and thin-layer chromatography; and detection with HPLC. Chromatographic conditions and methods of substance identification have been determined. The method allows the use of modest amounts of plant material (5-20 g), at which variability does not exceed 7%, and the total loss of substance is approximately 3%. The results of gibberellin A3 detection in buckwheat are presented.