Variations of the cyclic voltammetric behavior of pharmorubicin in an aqueous medium upon addition of DNA were studied and utilized for the determination of DNA. It was observed that the redox waves of pharmorubicin after binding to the large and slowly diffusing DNA almost disappeared. The anodic peak currents of pharmorubicin, when the concentrations were fixed at 2.0 x 10−5and 2.0 x 10−4mol/L, decreased linearly correlated to the concentration of DNA added in the range of 0 - 30.7 and 0 - 260.3 μg/ml, with the detection limits of 1.2 and 20.8 μg/ml, respectively. The proposed method exhibited good recovery and reproducibility for the determination of DNA. Furthermore, the binding constant and binding site size of the pharmorubicin-DNA interaction were also calculated.