A simple, accurate, precise and easy spectrophotometric method for the determination of carbamazepine and oxcarbazepine in pharmaceutical formulations using molybdenum blue method was developed by the authors. Aqueous solution of the drug sample on reaction with ammonium molybdate solution and hydrazine sulphate solution, on heating for 5 min at a temperature of 60°C gave a clear, stable and intense blue colored molybdenum blue complex. The resultant product of molybdenum blue showed a λmax at 823 nm for carbamazepine and 824.5 nm for oxcarbazepine. Beer’s law was found to be obeyed in the range 0.02-0.08 μg/ml for the farmer and 0.04-0.08 l.μg/ml for the latter. Correlation coefficient was found to be 0.998 and 0.997 for the two drugs under study. The method developed and validated was found to be sensitive, accurate, precise, easy and simple on comparison with the existing methods for quantitative analysis. The method was applied for the assay of the commercially available formulations of the drugs under study.