Topical ketoprofen patches are widely used in the treatment of musculoskeletal pain, but the pharmacokinetics of ketoprofen following topical application remain unclear. This open-label, single-dose pharmacokinetic study was designed to determine the concentrations of ketoprofen in the semitendinosus muscle/tendon and plasma after topical application or oral administration to patients scheduled for anterior cruciate ligament reconstruction. Two ketoprofen patches (20 mg each) were applied over the semitendinosus muscle/tendon for 1, 6, 14, or 20 h before surgery in 21 patients, while one sustained-release 150 mg ketoprofen capsule was administered to six patients 14 h before surgery. Ten untreated patients served as the control group. The main outcome measures were the semitendinosus muscle/tendon and plasma concentrations of ketoprofen at 1, 6, 14, and 20 h. Ketoprofen was detected in the semitendinosus muscle/tendon from about 1 h after topical application. The peak concentration was reached at 6 h, and it decreased gradually until 20 h, although the concentration at 20 h was still higher than that at 1 h. Unlike the tissue concentration, the plasma concentration of ketoprofen increased gradually after topical application. At 14 h, there was no significant difference of the tissue concentration between the topical and oral groups, although the plasma concentration was about 17-fold higher in the oral group than in the topical group. In conclusion, following topical application in a patch, ketoprofen shows rapid and sustained delivery to the underlying tissues without a significant increase of the plasma drug concentration.