The objective of the study was to develop a simple, accurate, precise and rapid a UV spectrophotometric i.e. first order derivative method for the determination of ambroxal hydrochloride and guaiphenesin in combined dosage form i.e. tablets by using distilled water as a solvent. The method was further validated by ICH guidelines. The proposed first order derivative method involves the measurement of absorbance of one drug at zero crossing point of other; hence wavelengths 216 nm and 264 nm were selected for the estimation of ambroxal hydrochloride and guaiphenesin respectively. The linearity of the proposed method was found in the concentration range of 1 to 10 μg /ml (r2= 0.9998) for ambroxal hydrochloride and 10 to 100 μg /ml (r2= 0.9999) for guaiphenesin respectively. The percentage mean recovery was found to be 99.885 % for ambroxal hydrochloride and 99.935 % for guaiphenesin respectively. The method was also statistically validated for its linearity, accuracy and precision. Both intra and inter day variations showed less percentage (%) RSD values indicating high grade of precision of this method.