A simple, accurate and sensitive spectrophotometric method has been developed for the estimation of rofecoxib in commercial preparations. The lactone ring in the drug is converted to hydroxy acid by sodium carbonate. 1,4-Napthoquinosulphonic acid acts as oxidizing agent and abstracts hydrogen ion from the hydroxy acid to form brown colored chromogen measured at the wavelength of maximum absorption 440 nm against reagent blank. The chromogen obeyed linearity over 20 to 120 $\mu$g/ml (r=0.9998). The method is satisfactorily applied for the analysis of pharmaceutical preparations containing rofecoxib. The results of the analysis were validated statistically and by recovery studies. The recovery ranged between 98.6 and 101.8%.