Researches of chemical transformation products of diclofenac sodium and glucosamine hydrochloride at their joint presence have been carried out by means of the gas chromatography-mass spectrometry. Mechanical mixes of substances were investigated before and after technological operations of humidifying and drying. It has been proven that one medicinal substance influences another. The formation of several reaction products during the chemical interaction between diclofenac sodium and glucosamine hydrochloride has been shown.