Aluminum (Al) inhibits root growthin acidic soil, but the site of action of Al remains unclear. We investigated whether the rate ofAl accumulation correlates to Al-indeced rapid root growth inhibition in rice seedings (Oryza sativa L. cv. Youngnam). Growth of roots was significantly inhibited by 100 $mu$M AlCl3 as early as 1h after the treatment. The inhibition of root growth was strongly dependent on Al concentration (I50=20$mu$M) and Al-exposure time(I50=23 min at 25$mu$M Al) in a solution of 10mM KCl and 1mM CaCl2 buffered by 10 mM Mes/KOH (PH 4.5). Using ICPES, massive uptake of Al by roots was observed even at 15 min treatment of 25 $mu$MAl. The kinetics of Al uptake by the roots closely corresponded to the inhibitory effects of Al on root growth. When the roots of seedlings were exposed to 50$mu$M Al for 1h, then sectioned and stained with hematoxylin, all cell types of the roots showed the presence of Al in the cytoplasm. These results indicate that Al was rapidly taken up into the root cells and thereby reduced root growth.