The interaction of anticancer drug adr amycin with DNA has been studied using voltammetric DNA biosensor. The binding mechanism of adriamycin was elucidated by using differential pulse voltammetry (DPV) at DNA modified glassy carbon fiber electrodes (GCFE). The decrease in guanine oxidation peak current at +0.9 V was used as an indicator for interaction mechanism in acetate buffer (pH 4.5). The studied drug-DNA interaction mechanism at charged electrode surface is similar to the in-vivo DNA-drug complex formation, where DNA is in close contact with charged phospholipid membranes and proteins. Thus, the fabricated biosensor helps in understanding the in-vivo mechanism of action of this anticancer drug.