The results suggest that the combination of different concentrations of morphine hydrochloride with haloperidol, metoclopramide hydrochloride, atropine sulphate, butylhyoscine bromide or ranitidine hydrochloride do not affect their stability when stored for 7 days up to 30 degrees C under the influence of ambient light. However, more robust stability-indicating methods are required to confirm these results. The proposed method is more useful for identifying combinations that are clearly incompatible than to identify those that are compatible.