Analytical method validation is an integral part of quality control system, since that gives reliability of analytical results obtained in a laboratory, to ensure that a product meets established quality parameters. We present the validation of an analytical method for quantification of naproxen sodium 550 mg tablet using ultraviolet spectrophotometry, proposed by Josette Lean. The statistical parameters used in the study were chosen taking into account the type category proposed analytical method according to USP 32 which were: The linearity, which measures the ability of the analytical method to produce results that are proportional to the concentration of analyte This is demonstrated in the validation to obtain a correlation coefficient r = 0.999954, being the minimum permissible value of 0.999. The precision of the analytical method is the degree of consistency or of dispersion of te...