Three-wavelength spectrophotometric method has been developed for the simultaneous estimation of atazanavir sulfate (ATZ) and ritonavir (RIT) in pharmaceutical preparations. The absorbance value at 279.7nm was used for the estimation of ATZ where RIT showed zero absorbance. The absorbance value for RIT was estimated by taking difference in absorbance at two wavelengths 248 nm and 252 nm. This method obeyed Beer’s law in the concentration range of 9-45 μg/mL for ATZ, and 3-15 µg/mL for RIT. The results of analysis have been validated statistically and recovery studies confirmed the accuracy of the proposed method. The percentage recoveries were found to be 101.3±0.4 for ATZ and 99.8± 0.2 for RIT. The assay values of atazanavir and ritonavir were found to be 100.7±0.7 and 103.0±1.2, respectively. The method was found to be simple, rapid, accurate, precise and sensitive. Hence, this method can be used for routine analysis of these drugs in formulations.