The clinical efficacy of the two topical analgesics, ketoprofen hydroalcoholic gel (Fastum gel) and diclofenac emulgel, for osteoarthritis of the knee was studied. There were 85 patients who underwent the trial. They were randomly allocated into 2 groups, the diclofenac group, 42 patients (4 males and 38 females) receiving the diclofenac emulgel at the painfull site four times a day for 4 weeks, and the ketoprofen group, 43 patients (9 males and 34 females) receiving the ketoprofen hydroalcoholic gel four times a day for 4 weeks at the painful knee. Golberg's knee scoring was used to evaluate the patients before the trial, at the end of the first, second and fourth weeks. The ketoprofen group had poorer a score before the trial, however, both groups had improvement in their knee functions, knee score and pain. There was no significant difference between the groups at the end of the study. There was no serious side effect in both groups. Ketoprofen hydroalcoholic gel gave persuasive results in the treatment of knee arthrosis stage I and II.