Thirteen men with a mean age of 40 years had glenohumeral arthritis and symptoms of stiffness, pain, and locking of the joint at presentation. Provocative test results for anterior or posterior instability were negative. Computed tomography detected posterior humeral head subluxation relative to the glenoid and posterior cartilage wear. All patients demonstrated this posterior subluxation in the absence of posterior glenoid erosion. The mean glenoid retroversion was increased (14.5 degrees ). Increased glenoid retroversion was observed in the contralateral shoulder in 4 cases, and marked static posterior subluxation was noted in the contralateral shoulder in 3 cases. Various surgical procedures were performed in 5 patients to correct this arthrogenic posterior subluxation. Patients who underwent surgery were reviewed at a mean follow-up of 46 months with physical examination and computed tomography. The patients with the longer follow-up showed a progression of arthritis, and all cases showed persistent or recurrent posterior humeral subluxation. Glenohumeral arthritis with static posterior subluxation of the humeral head in the young adult could be the first stage of primary glenohumeral arthritis, predating signs of posterior glenoid erosion. Our attempts to correct this static posterior subluxation failed.