37 consecutive patients with radial tunnel syndrome treated by decompression of the posterior interosseous nerve and application of a free fat transplant were retrospectively evaluated 3.5 (1-5) years post-operatively by an independent observer. Substantial pain relief was reported by 13 patients and 15 patients were satisfied with the outcome. 16 of 35 patients returned to their preoperative employment. There were complications in 12 cases, including two radial nerve pareses. Preoperative and operative findings did not correlate to the outcome. Judging from this study, the symptoms and signs used as diagnostic criteria for radial tunnel syndrome may be unreliable and the results of posterior interosseous nerve decompression unpredictable.