Efficiency of arsenic removal from contaminated soil by two species of vetiver grasses, Vetiveria zizanioides (Linn.) Nash [Surat Thani ecotype] and Vetiveria nemoralis (Balansa) A. Camus [Prachuabkirikhan ecotype] was studied in difference concentration of arsenic ; 0 50 75 100 125 and 150 mgAs/kg soil dry weight, by disodium hydrogen arsenate (Na1HAs04•7H20). The growth ability; number of plants per clump, diameter of clump, height and dry weight were recorded every 15 days, on 6 consecutive occasions over a 90 day-trial period. It was found that growth of both species were not affected by arsenic (p>0.05). In addition, Vetiveria zizanioides (Linn.) Nash had number of plants per clump and diameter of clump higher than of Vetiveria nemoralis (Balansa) A. Camus. In contrast, the height and dry weight of Vetiveria nemoralis (Balansa) A. Camus was higher than of Vetiveria zizanioides (Linn.) Nash. Accumulation of arsenic in roots was higher than in leaves. Amount of arsenic accumulation in Vetiveria zizanioides (Linn.) Nash was more than in Vetiveria nemoralis (Balansa) A. Camus. In addition, arsenic removal efficiency by two species increased by exposed time . The highest efficiency of Vetiveria zizanioides (Linn.) Nash was 0.0488 %, at experimental time of 90 days in treatment of 75 mgAs/kg soil dry weight, and the highest efficiency of Vetiveria nemoralis (Balansa) A. Camus was 0.0398 %, at experimental time of 90 days in treatment of 125 mgAs/kg soil dry weight.