M.MOUSAMI*, A.KRISHNAMANJARI PAWAR, D.V.V. RAMA RAJU Zileuton, RP-HPLC, isocratic mode. 1558-1568 Volume 4, Issue 6 November - December 2013 Zileuton is an antiasthmatic durg. It acts by inhibiting 5-lipoxygenase enzyme thereby preventing formation of leukotrienes that cause bronchoconstriction. The new, simple, accurate, sensitive robust, reproducible, isocratic RP-HPLC method was developed using Xterra C 18 column (5m, 250 4.6mm), at 1ml/min flow rate with 10min run time using 20l injection volume and 25C temperature conditions. The detection wavelength used is 299.5nm. Retention time is obtained at 3.155min. Linearity was established in the range of 2 to 10g/ml with 0.999 correlation coefficient and % recovery of 99.6 99.9%. The method is validated according to the specifications in ICH guidelines.