A validated RP HPLC method for the estimation of Atazanavir sulphate in capsule dosage form on Egilent TC C18 (2) 250 x 4.6 mm, 5 μ column using mobile phase composition of water: acetonitrile (20:80 v/v) pH adjusted to3. Flow rate was maintained at 1 ml/min at an ambient temperature. Quantification was achieved with ultraviolet (DAD) detection at 255 nm. The retention time obtained for Atazanavir sulphate was at 3.7 min. The detector response was linear in the concentration range of 10 – 80 μg/ml. This method has been validated and shown to be specific, sensitive, precise, linear, accurate, rugged, robust and fast. Hence, this method can be applied for routine quality control of Atazanavir sulphate in capsule dosage forms as well as in bulk drug.