A simple, direct and sensitive spectrophotometric method for the determination of the intact N-desmethyldiazepam in the presence of its degradation products, 2-amino-5-chlorobenzophenone and glycine, is developed. The proposed procedure is based on direct measurement of the absorbance of its acidified methanolic solution at 361 nm. The procedure determines 8–56 mcg ml−1of N-desmethyldiazepam with an accuracy of 100.2 ± 0.51%. The proposed procedure retains its accuracy in presence of up to 80% of the different degradation products. The procedure is applied successfully for the determination of N-desmethyldiazepam in bulk powder, tablets and drops.