Highly sensitive method for the determination of genotoxic impurities such as Alkyl Para Toluene Sulfonates (APTSs) in brinzolamide using RP-LC has been presented in the present paper. APTSs were determined by RP-LC method using Waters Symmetry C18 (250 × 4.6 mm), 5 μ column as stationary phase. Column temperature maintained 30°C, injection volume 20 μl, flow rare was 1.5 ml/min, sample cooler temperature 5°C and run time was 30 min. pH 2.50 phosphate buffer is used. The mixture of buffer and acetonitrile in 50:50 (v/v) was used as mobile phase. The method validation has been carried as per International Conference on Harmonization guidelines. Limit of Quantitation (LOQ) was found in the range of 1.1-2.2 μg/ml for APTSs.