Bladder cancer is a common but serious malignancy. It is widely accepted that chemoprevention may be an effective way to decrease the rate of recurrence and morbidity. We first determined antigrowth and apoptosis-induction activity of fucoxanthin from dietary Laminaria japonica against EJ-1 human bladder cancers. Fucoxanthin significantly reduced the cell viability in a dose- and time-dependent manner. The induction of apoptosis in EJ-1 cells was characterized by morphological changes, DNA ladder, and increased percentage of hypodiploid cells, activating caspase-3 activity. The ratio of apoptotic cells reached >93% after treatment for 72 h with 20 microM fucoxanthin. The findings obtained indicate that fucoxanthin may act as a chemopreventive and/or chemotherapeutic carotenoid in bladder cancer cells by modulating cell viability.