A new, simple, rapid, accurate and reproducible reverse phase high performance liquid chromatographic method with UV detection was developed and used for the estimation of abacavir sulphate and fosamprenavir in bulk and in their pharmaceutical dosage forms. High performance liquid chromatography was carried out on a Waters Spherisorb ODSI (250x4.6mm with 5 μm particle size) column with a flow rate 1.0 mL.min-1 using a mobile phase consisting of methanol: phosphate buffer (80:20, v/v) containing 15mM phosphoric acid at pH 6.2. The detection was carried out at 275 nm and the run time was 5 min. For the sensitive determination of abacavir, fosamprenavir was used as an internal standard and for determination of fosamprenavir vice versa. Using these conditions, both antiviral drugs were analyzed simultaneously with the same method and same chromatographic conditions. The linearity was found to be in the range of 0.25-75 μg.min-1 and 0.50-75 μg.min-1 for abacavir and fosamprenavir, respectively. The retention times for fosamprenavir and abacavir were 2.48 and 4.04 min, respectively. The proposed method was validated according to ICH and USP guidelines and application of the method to tablet dosage forms were also performed.