Electroanalytical procedure for the determination of nephrotoxic aristolochic acid-I in the medicinal plant been developed in the presence of potential interferences of lead and cadmium by square wave voltametry (SWV). Among the phosphate buffers of pH values at 5.0, 6.1 6.5 and 7.0 the Phosphate buffers of pH 6.1 yielded the most accurate analysis of AA-I in the presence of Pb$^{2+}$ and Cd$^{2+}$, Pb$^{2+}$ was precipitated as Pb(HPO$_4$) and did not appear in the SW voltammogram while Cd$^{2+}$ appeared at -0.564 V which was well resolved from AA-I at -0.416 V. When the Ip of AA-I was plotted vs. concentrations between 1.67${ imes}$10$^{-8}$ M and 1.67${ imes}$10$^{-6}$ M in the presence of Pb$^{2+}$ and Cd$^{2+}$, a linear calibration curve was obtained with a slope of 6${ imes}$10$^8$ nA/M and a correlation coefficient of 0.9999. The present method was applied to determine AA in the dried natural products of Aristolochia contorta Bunge; Total AA in the dried root and the ripe fructus of Aristolochia contorta Bunge were found as 25 ${pm}$ 1 ${mu}$g/g and 85${pm}$ 3 ${mu}$g/g, respectively.