In a randomized, double blind, multicentre study with 4 weeks follow-up of 290 patients with osteoarthritis of the knee joint, a topical NSAID (eltenac) was compared with oral diclofenac and placebo. The main outcome, Lequesne's Index and pain by VAS showed no statistically significant differences between neither of the active treatments and placebo for the total study population. However, in patients with more severe symptoms, both active groups showed statistically significant differences to placebo. No severe adverse drug reactions were seen but the number of GI reactions were three times higher in the diclofenac group compared to the topical treatment. Local skin reactions were twice as frequent in the eltenac than in the placebo group. Taking into account the nature of the treatment for a chronic disease like OA, our results indicate that eltenac gel could be a safe alternative to oral NSAIDs.