Proximal radial nerve compression occurs infrequently and is diagnosed successfully even less frequently. A large clinical series of patients with proximal radial nerve compression neuropathy was reviewed to determine better the common symptoms, physical findings, and electrodiagnostic findings, and to identify the predictors of better or worse outcome after surgical decompression. Seventy-nine proximal radial compression neuropathies were treated in 71 patients by the same surgeon between 1991 and 2000. The most consistent symptoms were deep aching pain in the forearm, pain radiation to the neck and shoulder, and a "heavy" sensation of the affected arm. The most common physical findings were tenderness over the radial nerve at the supinator muscle level, pain on resisted supination, and the presence of a Tinel sign over the radial forearm. Electrophysiologic studies were of limited value in diagnosis, with 90% of patients having normal findings. On operation, prominent pathology of the posterior interosseous nerve was observed in 36 of 79 limbs (46%). Follow-up ranged from 12 to 86 months (mean, 21 months) with no significant complications or recurrence of symptoms. Of the 79 nerve decompressions, 77% had excellent recovery and 20% were judged to be good. Of 69 patients employed when treated, 60 resumed gainful employment, including 53 who returned to their regular jobs. Proximal radial compression neuropathies are uncommon but present with a basic constellation of symptoms and physical findings, and decompression can provide excellent relief of symptoms.