Anthocyanin pigments accumulated in a cell line derived from storage-root explants of sweet potato (Ipomoea batatas L.) cv 'Ayamurasaki'. Somatic pro-embryos were induced on the explants cultured on Murashige and Skoog medium supplemented with 1 mg/l 2,4-D. The pro-embryo structures produced callus when transferred to MS medium with 0.5 mg/l 2,4-D. A cell line was isolated from this callus which accumulated anthocyanin pigment. The color value of the pigment extracted after 27 days of culture in MS medium with 2 mg/l 2,4-D was 8.2, which was very close to that of a pigment extracted from roots, which was 8.9. Most of the pigments from the cell extract were hydrophilic and appeared on the ODS-column HPLC with a lower retention time than the main anthocyanins of the root tissues. The majority of the pigments were identical with the root anthocyanins. Cell line-specific anthocyanins were detected.