A simple, specific, accurate and precise First order derivative UV Spectrophptometry method was developed and validated for the estimation of Efavirenz in bulk and pharmaceutical dosage forms. The stock solution was prepared by weighing 100 mg of standard EFV in 100 ml volumetric flask with methanol and water (50:50) (Stock solution I). The final stock solution was made to produce 100µg/ml with methanol and water (50:50).Further dilutions were prepared as per procedure. The first derivative amplitude at 238.50 nm was selected for the assay. The linearity was found in the concentration range of 3-18 µg/ml. The Correlation coefficient was 0.999. The regression equation was found to be y = 0.038 x - 0.001. The method was validated for linearity, sensitivity, precision, accuracy and ruggedness. The limit of detection and limit of quantification for estimation of EFV was found to be 0.078µg/ml and 0.236 µg/ml, respectively. Recovery of EFV was found to be in the range of 99.08-99.97 %. Proposed method was successfully applied for the quantitative determination of EFV in bulk and pharmaceutical dosage forms. These methods were tested and validated for various parameters according to ICH guidelines. The proposed methods were successfully applied for the determination of EFV in capsule formulations. This method was successfully applied to the pharmaceutical dosage form and there no interference of capsule excipients was found in recovery study. Key words: Efavirenz (EFV), ICH (International Conference on Harmonization), and UV- Spectrophotometric method.