The accumulation of only one anthocyanin, cyanidin 3-glucoside, in cell-suspension cultures of plane tree (Platanus aceriflia) is reported for the first time. During a time span of 6 years, no new anthocyanin was detected and cyanidin 3-glucoside was maintained at about 35 mg l(-1) cell culture medium. This stable cell culture system could therefore be used for the biotechnological production of cyanidin 3-glucoside.