Background: Little is currently known regarding the cancer preventive potential of cyanidin-3-O-b-glucopyranoside (Cy-g) apart from its antioxidant activity. Methods: We tested Cy-g on Jurkat and HL-60 leukemia cell lines and, to help elucidate whether the effects of Cy-g are specific for cancer cells, also on normal T lymphocytes. Results: Cy-g-induced apoptosis on all three cell systems, and this indicated that Cy-g was not selective towards leukemia cells. Moreover, Cy-g caused HL-60 differentiation. The induction of apoptosis and cytodifferentiation involved different proteins, thus suggesting that Cy-g-induced apoptosis and cytodifferentiation are two distinct events. Conclusions: Although in vitro, our findings indicate that Cy-g possess some interesting biological properties that should encourage further investigation as regards its chemotherapeutic potential.