The objective of present study was to develop simple, accurate, precise, cost effective and reliable analytical method for estimation of Diclofenac potassium (DCL), Serratiopeptidase (SER) and Paracetamol (PCM) in combined tablet dosage form. First order derivative simultaneous estimation was carried out by using UV visible double beam spectrophotometer. Developed method uses a solvent methanol: distiied water (40:60) for wavelength determination. Sample was scanned at 200-400 nm and working wavelength (252 nm, 276 nm and 330 nm) was detected. Validation of simultaneous spectrophotometric methods was performed with different parameters. In first order derivative method, at 252 nm, 276 nm SER, at 330 nm DCL and at 252 nm, 276 nm PCM showed significant absorbance. Linearity of SER, DCL and PCM was 2 µg/ml to 15 µg/ml, 2 µg/ml to 30 µg/ml and 2 µg/ml to 80 µg/ml respectively. The method precisions were exemplified by relative standard deviations of 1.82% and 1.77% for SER, 1.42% and 1.42% for DCL and 1.60% and 1.82% for PCM in intra and inter day precision respectively. The %R.S.D. is less than 2% as required by USP and ICH guidelines. Present study revealed that developed and validated first order derivative UV spectroscopy method for simultaneous estimation of SER, DCL and PCM was found to be least time consuming, accurate, precise and linear.