Objective: To develop and validate reverse phase-high performance liquid chromatographic method for estimation of olanzapine in bulk and tablet dosage form. Methods:Chromatographic analysis was performed on XTerra C18 (150×3.5 mm inner diameter, 5 µm) column using a mobile phase consisting of buffer (potassium dihydrogen phosphate) and methanol (45:55% v/v) with a flow rate of 0.6 ml/minutes. The detection was carried out at 247 nm. Results:The calibration curve of olanzapine was linear in the range of 30-70 µg/ml. The mean % assay of marketed formulation was found to be 100.2%, and % recovery was observed in the range of 98-102%. Relative standard deviation for the precision study was found <2%. Conclusion:The developed method is simple, precise and rapid, making it suitable for estimation of olanzapine in bulk and tablet dosage form.