Five Artemisia capillaris plants were selected at random from among a bed of twenty plants cultivated in a field for one year. Several branches were collected from each plant once a month, except in August and October, when two collections were made during budding and flowering. Each organ (leaf, stem, and capitulum) was separated from the branch and dried, and later analyzed for capillarisn and 6, 7-dimethylesculetin content by high-performance liquid chromatography (HPLC).The capillarisn and 6, 7-dimethylesculetin content reached maximum levels in the leaf just before the appearance of flower buds at end of July. About one month later, at the end of August during budding and flowering, capillarisin content in the capitulum reached a peak and then decreased. On the other hand, 6, 7-dimethylescuretin content reached a maximum at the beginning of September, two weeks after the capillarisn maximum.The results suggest that the most appropriate time to harvest A. capillaris for use as a crude drug is between the flower bud stage and early flower stage, from late August to early September.