The suprascapular nerve passes through the spinoglenoid notch with a risk of entrapment. This results in distal nerve lesion characterized by isolated paralysis of the infraspinatus muscle and, most often, by shoulder pain. We report 7 clinical and electromyographical cases of pure infraspinatus muscle paralysis. The value of the electrodiagnosis, which demonstrated prolonged suprascapular distal nerve latencies (over 5 milliseconds) in the infraspinatus muscle affected while latencies were normal in the supraspinatus muscle, is emphasized. Mechanical factors were associated with paralysis in 5 cases. Compressive synovial cysts were found in 2 patients operated upon. Surgical enlargement of the spinoglenoid notch regularly and rapidly relieves pain and sometimes helps in recovery of the infraspinatus muscle.