[Introduction] In our-previous study of shoulder stiffness,we found that patients with shoulder stiffness had increased IL-1β expression in lesion tissue.Our recent data also showed anti-inflammatory effect of ESWT.We hypothesized that ESWT might be beneficial for rotator cuff lesions with shoulder stiffness.[Material and Method] We performed a prospective randomized double-blind study.The criterion for shoulder stiffness was ≥50%loss of passive range of motion(ROM).Patients were randomly divided to receive either shockwave or conservative treatment(control group)based on statistical randomization.In the shockwave group,we used OrthospecTM Extracorporeal Shock Wave Therapy 3000 impulse 24KV(0.32mJ/mm2)focus at two points at an area 1cm proximal to the insertion of supraspinatus.The sham treatment entailed use of the device in which the generator was disconnected.The treated area was inspected for local swelling,ecchymosis,or hematoma.VAS and Constant score were used for measurement.[Results] 21 patients were enrolled.Three patients underwent surgery 4 weeks,3 months and 6 months after study respectively,due to severe symptoms.At the latest follow-up,10 patients had sum of ROM >= 300°.At 6 months after treatment,the ESWT group had significantly better ROM and Constant score when compared with control group.[Discussion] Although ROM and symptoms improved in both groups,the ESWT group had better improvement than the control group 6 months after treatment.This phenomenon may be attributable to the physiological effects of ESWT and the slow progressive nature of shoulder stiffness.[Conclusion] ESWT may be beneficial for shoulder stiffness associated with rotator cuff lesions.