A simple and sensitive spectrophotometric method was developed and validated for the determination of mesalamine in bulk and pharmaceutical formulations. The method was based on the reaction of drug with the mixture of potassium iodate and potassium iodide. The method was linear in the range of 15-50µg/ml. The absorbance was measured at 487nm. The method was validated with respect to accuracy, precision, specificity, ruggedness, and robustness, limit of detection and limit of quantitation. Thus a simple and precise method has been developed.