The determination of berberine in Berberis koreana was examined by the high performance liquid chromatography using ${mu}-Bondapak$ $C_{18}$ column and $CH_3CN/phosphate$ buffer (pH 5.2) (60/40) as a mobile phase. The seasonal variations of berberine contents in Berberis koreana were as follows; 1) In roots, the average berberine content was 0.94% with the highest level of 1.32% in October. 2) In stems, their average berberine content was about 0.1% and in March, April, October and November, the contents were relatively high. 3) In leaves, however, the content was as low as 0.005%. According to the experimental results obtained, we found that Berberis koreana roots can serve as the useful natural plant resources for the berberine and October is the optimal season for the collection.