A randomized pilot study, comparing oral naproxen and a single betamethasone injection, was carried out in 21 patients suffering from lateral epicondylitis of the humerus ("tennis elbow"). The naproxen dosage was 250 mg per day for two weeks. Six milligrams of betamethasone in a long-acting form was given as a local injection. To achieve "blindness," the patients receiving naproxen were also given an injection of saline into the area of maximal tenderness at the epicondyle, while the patients getting the betamethasone-injection were given oral placebo tablets. At a clinical control after two weeks, five of the ten patients receiving naproxen and five of the 11 patients receiving betamethasone injection were improved. Thus, no apparent difference in effect could be noted at an evaluation after two weeks' treatment. No significant side effects were noted with any of the treatments.