Shoot, adventitious root and callus cultures of Ajuga reptans L. were established, and the production of three caffeic acid derivatives [rosmarinic acid (RA), lithospermic acid (LA) and lithospermic acid B (LAB)] in the tissue cultures was investigated. A. reptans plantlets, cultured in vivo and in vitro, accumulated three polyphenols analyzed, although the contents were not so high (RA: 0.001-0.028%, LA: 0.036-0.106% and LAB: 0.002-0.031%, as dry weight). Higher productivity of LA compared to those of RA and LAB, found in A. reptans plantlets, was simiilar to ones which have been also observed in Salvia in Lamiaceae and Lithospermum and Heliotropium in Boraginaceae. Adventitious roots cultured in 1/2 MS liquid medium supplemented with 1 mg/l NAA produced high content (0.045% as dry weight) of LAB, which level was identical with those of the adventitious and hairy root cultures of Ocimum basilicum. The maximum RA content (0.008%, as dry weight) in A. reptans adventitious roots in the same medium was not so high, which level was almost 1/1000 of that of the adventitious and hairy root cultures of Ocimum basilicum and also 1/4 of that of the adventitious root cultures of Heliotropium pervianum. A. reptans calli cultured on 1/2 MS solid medium containing 1 mg/l 2,4-D produced large amount of RA (0.071% as dry weight), while the calli on 1/2 MS solid medium supplemented with 2 mg/l NAA-0.1mg/l BA, produced LA (0.113% as dry weight) as the major polyphenol. The level of the maximum RA content observed in A. reptans calli was almost 1/100 of that of Coleus blumei cells and also 1/10 of those of Lithospermum erythrorhizon and Salvia officinalis cell cultures. In this experiment. A. reptans was clarified to be a resource plant which produce caffeic acid derivatives (RA, LA and LAB), one of the important natural antioxidants. Tissue cultures of this plant, such as shoot, adventitious root and callus, also seemed to be suitable materials for biosynthetic study of these caffeic acid derivatives.