Abstract: Effects of Al and Ca interactions on the sugar compositions and molecular mass of hemicellulosic polysaccharides were examined in the roots of an Al sensitive wheat cultivar (Triticum aestivum L.). Seedlings were grown in nutrient solution for 7 days and then exposed to treatment solutions containing Al (0, 50 μM) and Ca (0, 2500 μM) in a 500 μM CaCl2 solution at pH 4.5 for 8 days. High Ca supply (2500 μM) improved the root growth significantly. The contents of pectin and hemicellulose were increased under Al stressed condition and this increase was conspicuous in hemicellulosic polysaccharides. The increase in the hemicellulose content was attributed to increases in arabinose, xylose and glucose in neutral sugars. Calcium supply decreased a little these contents in Al stressed cell walls. The elution profile of molecular mass of hemicellulosic polysaccharides was shifted to higher molecular mass region by Al stress compared to control and the Ca treatment with Al shifted slightly lower molecular mass regions. Aluminum treatment increased the estimated arabinoxylan and β-glucan contents and Ca treatment with Al decreased these contents. Aluminum treatment decreased significantly the β-glucanase activity, whereas Ca treatment with Al increased the activity. These results suggest that the modulation of the activity of β-glucanase with Al stress may be involved in part in the alteration of the molecular mass of hemicellulosic polysaccharides. The increase in molecular mass of hemicellulosic polysaccharides with Al stress may induce the mechanical rigidity of the cell wall and inhibit the root growth. High Ca treatment with Al is considered to reduce the mechanical rigidity of the cell wall and improve root growth.