This study is aimed at comparing the efficacy and safety of loxoprofen sodium hydrogel patch (LX-P) with loxoprofen sodium tablet (LX-T) in patients with knee osteoarthritis (OA). One hundred sixty-nine patients were enrolled in a randomized, controlled, double-blind, double-dummy, multicenter, non-inferiority trial of LX-P. Patients were randomly assigned to either LX-P or LX-T groups for a 4-week treatment. The primary efficacy endpoint was the proportion of patients with an overall improvement of >= 50 %, and the secondary efficacy endpoint was the proportion of patients with an improvement of >= 25 % from baseline in each of the seven main symptoms. The non-inferiority trial was based on a power of 80 % and significance level of 2.5 % with a non-inferiority margin of -10 %. In both intention-to-treat (ITT) and per-protocol (PP) analyses, LX-P was as effective as LX-T in regard to the primary endpoint. In the ITT analysis, the difference between the two groups was 12.6 % [95 % confidence interval, -1.7 to 26.9 %]. No significant differences were found between the two groups in any of the secondary efficacy outcomes. A lower incidence of adverse events was observed in LX-P group; however, the difference was not statistically significant. No serious adverse events were reported in the LX-P group, whereas one case was reported in LX-T group. Based on the present study, topical loxoprofen patch was non-inferior to oral loxoprofen in patients with knee osteoarthritis.