In the present study, areca nut extracts (ANE) administered to male rats by gavage at a dose of 100 mg/kg/day for a period of 15, 30, or 45 days resulted in signs of reproductive toxicity. ANE administration resulted in a significant decline (30-57% in epididymal sperm count and 27-61% in sperm motility) as well as substantial abnormalities in sperm morphology. Significant variances in activities of antioxidant enzymes were also observed. Malondialdehyde (MDA) levels, which represent the level of lipid peroxidation, increased by 16-188% and levels of sialic acid decreased by 2-46% compared with that in controls. These results indicate that ANE induced spermatogenic damage, as indicated by a decrease in sperm counts and sperm motility as well as the activity of antioxidant enzymes, an increase in sperm abnormalities, and alterations in sialic acid and MDA levels. Such effects reflect that ANE administration resulted in reactive oxygen species (ROS)-induced oxidative stress in the testis, cauda epididymis, and sperm of male rats. Crown Copyright (C) 2010 Published by Elsevier B.V. All rights reserved.