Abstract: Objective To test arsenic species in urine after intaking seaweed,and investigate the characteristics of arsenic metabolism.Methods Arsenic species in urine were detected with hydride generation atomic absorption spectroscopy.Results There was a significant increase in the urinary concentration of iAs at twelve hours after intaking seaw eed,increase of DMA at twelve,twenty-four and thirty-six hours after intaking seaweed in male group.No significant increase of MMA and TMA was detected in the male group.There was a significant increase in the urinary concentration of iAs at nine,twelve and thirty-six hours after intaking seaweed,the increase of MMA at five,two and twenty-four hours after intaking seaweed,increase of DMA from three to seventy-two hour after intaking seaweed in female group.No significant increase of TMA was detected in the female group.Conclusion There was a difference between male and female in the metabolism of arsenic.Male is more susceptible than female.