Abacavir has an antiretroviral. activity against HIV and is oxidizable at the glassy carbon electrode. Cyclic voltammetry studies showed one well-defined oxidation wave or splitted two waves depending on pH. The oxidation was irreversible and exhibited diffusion controlled process depending on pH. The mechanism of the oxidation process was discussed. According to the linear relation between the peak current and the concentration, differential pulse voltammetric (DPV) and square wave voltammetric (SWV) methods for its quantitative determination in pharmaceutical dosage forms and biological fluids were developed. These two voltammetric techniques for the determination of abacavir in Britton-Robinson buffer at pH 2.0, which allows quantitation over the 8 x 10(-7) to 2 x 10(-4) M range in supporting electrolyte for both methods were proposed. The linear response was obtained in Britton-Robinson buffer in the ranges of 1 x 10(-5) to 1 x 10(-4) M for spiked urine sample at pH 2.0 and 2 x 10(-5) to 2 x 10(-4) M for spiked serum samples at pH 3.0 for both techniques. The repeatability and reproducibility of the methods for all media (such as supporting electrolyte, serum and urine samples) were determined. Precision and accuracy were also checked in all media. The standard addition method was used in biological media. No electroactive interferences from the endogenous substances were found in the biological fluids. (C) 2004 Elsevier Ltd. All rights reserved.