In an among-group comparison, all three modalities provided nearly comparable clinical efficacy after a three-week symptomatic treatment of OA of the knee. Nevertheless, a trend toward greatest improvement, determined by magnitude of changes in most outcome variables, was likely to be found in THC group. Furthermore there were statistically better physician's overall opinion of improvement in favor of THC compared to TM, and significantly better improvement of Lequesne's functional index in favor of THC compared to ibuprofen, whereas no adverse event was reported in THC group. These findings suggest that THC should be an attractive alternative option in symptomatic treatment of OA of the knee, in comparison to TM or oral ibuprofen. It is unclear whether combination of TM and THC, as commonly seen in real situation of traditional practices, would contribute to better clinical outcomes. This interesting issue warrants further investigation.