Purpose: To investigate the effectiveness of treatment with ultrasound-guided injection versus blind injection in the treatment of subacromial bursitis. Although blind injection of the subacromial bursa is a frequently used treatment, a misplaced injection may produce a poor response. Ultrasound-guided injection is assumed to be more accurate than blind injection. Subjects and Methods: We tested 13 shoulders of 10 patients (mean age, 57.6 years) with subacromial bursitis. These patients received ultrasound-guided subacromial injection and blind subacromial injection of 1% lidocaine (2 ml) administered by the same orthopedic surgeon. The effectiveness of the treatment was indicated by points on a pain scale. Evaluation times were 1, 5, 10, 15, 20, 25, and 30 minutes before and after injection. Results: Average measured level of pain with ultrasound-guided subacromial injection was markedly lower than with blind subacromial injection at all time intervals, and the pain values were significantly lower at 1 min, 5 min, 10 min, 20 min, 25 min, 30 min after injection (PConclusion: The ultrasound-guided injection technique can result in significant reduction in shoulder pain as compared with the blind injection technique.