The therapeutic substances in solution prepared in pharmaceutical laboratories (prescribed drugs) must preserve their activity. Therefore, they must be stable throughout the period of storage in home conditions. The maintenance of stability is particularly difficult for morphine hydrochloride solutions administered orally to cancer patients at the last stage of the disease being at home. This study, aiming at the assessment of stability of morphine hydrochloride solutions, was performed on samples of 0.5% water solutions of the drug alone, 0.25% and 0.5% solutions of the drug in water with chloroform as well as injection solutions (Morphinum hydrochloricum, 20 mg, Polfa Warsaw). All the samples were kept at 20 degrees C for six months. Throughout this time observations were made to detect changes in their appearence and pH values. Their qualitative composition was determined by TLC and the content of morphine was checked by UV spectrophotometry in an environment of 0.1 mol/l of hydrochloric acid at 285 nm. Results of the kinetic study permitted drawing conclusions as to the mechanism of the decomposition of morphine hydrochloride in the solutions studied - according to a simple first order reaction and determination of the rate constants (k, s(-1)) of the process. Results of the chromatographic and spectrophotometric study did not show differences in the stability of water and chloroform/water solutions of morphine hydrochloride studied after 4 weeks and 6 months. After that time the decrease of morphine content was 10 and 25%, respectively.