Plant-cultured cells are often highly heterogeneous in secondary metabolite productivity. The industrial application for large-scale metabolite production requires establishment of a stable high-producing cell line. In this study, image analysis of the individual cell is investigated as a method for evaluation of a heterogeneous cell population, and compared with the conventional method of estimation, which is based on average-cell productivity. Among strawberry cells producing anthocyanins, cells with a wide-range of pigment concentration were observed and maximum anthocyanin content was 10 times higher than the average value. In addition, a change of the frequency distribution was revealed in batch cultivation. (C) 2000 John Wiley & Sons, Inc.