In this research, the capacity of three phytoremedial species in an agricultural soil highly contaminated with Arsenic (As) of the Tiliche San José Irrigation Board, Cotopaxi-Ecuador, was evaluated. A Full Randomized Design was used with three treatments (Canna indica L., Medicago sativa L. and Cortaderia Nitida L.) and three replications; the comparison of means was performed with Tukey's test at 5% significance. The reduction of arsenic in the agricultural soil, transfer factor (TF), bioaccumulation (BF) and development of the species at 90 and 210 after transplantation were determined. The results revealed that the bioremediation of As with Medicago sativa L. is highly significant (p<0.01) achieving a reduction of 85±1.5%, but decreased with Canna indica L. (70±2%) and Cortaderia Nitida (45±0.7%) at the end of the experiment. However, the treatments did not achieve even 1/3 of the height of their species under normal conditions, evidencing the complex relationship between the accumulation of As and plant development. The phytoremediation of As was superior with Medicago sativa L. due to its greater transfer capacity and bioaccumulation, so it absorbs As in its tissues, while reducing the concentration of it in highly contaminated soil. But, Cortaderia nítida, a plant from the area with slow growth and reduction of Ace, could be a long-term alternative.