The interaction of fulvestrant with double-stranded DNA (dsDNA) was studied by means of differential pulse voltammetry (DPV) at dsDNA modified pencil graphite electrode (PGE). The decrease in intensity of the guanine oxidation signals was used as an indicator for the interaction mechanism and sensitive determination of fulvestrant in pH 4.80 acetate buffer (30% ethanol). A linear dependence of the guanine oxidation signals was observed within the range of 1.00-20.00 mu g/mL fulvestrant, with a detection limit of 0.41 mu g/mL The determination method was validated according to the standard validation procedure. The proposed method was applied to fulvestrant pharmaceutical dosage form. (c) 2011 Elsevier Ltd. All rights reserved.