The present work describes a simple, precise and accurate HPLC method for estimation of montelukast sodium in bulk and in tablet dosage form. The separation was achieved by using octadecylsilane column (C18) and acetonitrile: 1 mM sodium acetate adjusted to pH 6.3 with acetic acid in proportion of 90: 10 v/v as mobile phase, at a flow rate of 1.5 ml/min. Detection was carried out at 285 nm. The retention time of montelukast sodium was found to be 3.4 min. The limit of detection was found 1.31 mu g/ml and limit of quantification 3.97 mu g/ml. The accuracy and reliability of the proposed method was ascertained by evaluating various validation parameters like linearity (1-100 mu g/ml), precision, accuracy and specificity according to ICH guidelines. The proposed method provides an accurate and precise quality control tool for routine analysis of montelukast sodium in bulk and in tablet dosage form.