A simple, specific, sensitive, precise and stability-indicating reversed phase high performance liquid chromatographic method was developed and validated for the simultaneous determination of thiocolchicoside and aceclofenac, using a RP-18 column and a mobile phase composed of 0.1% trifluoroacetic acid: acetonitrile (45:55). The retention time of thiocolchicoside and aceclofenac were found to be 2.35 and 13.2 min, respectively. Linearity was established for both thiocolchicoside and aceclofenac in the range of 0.08-0.8 and 1-10 µg/ml. Both the drugs were subjected to acid, alkali and neutral hydrolysis, oxidation, dry heat, and photolytic degradation. The degradation studies indicated that both thiocolchicoside and aceclofenac were susceptible to acid, alkaline and neutral hydrolysis. The degradation products of thiocolchicoside and aceclofenac were well resolved from the pure drugs with significant differences in the retention time values. This method can be successfully employed for simultaneous quantitative analysis of thiocolchicoside and aceclofenac in bulk drugs and formulations.