The application of the arthroscope to the shoulder joint has evolved in recent years for the purpose of diagnosis and treatment. This paper presented 11 cases with various shoulder diseases treated by arthroscopy during the period from January, 1984 to September, 1985 in the Department of Orthopedic Surgery, College of Medicine, Soon Chun Hyang University. The advantages of the arthroscopy were as follows: 1. The arthroscopy made it easier to diagnose the unsolved cases by direct biopsy on the pathologic lesions in the joint. 2. The damage on the inside and outside of the shoulder joint was minimal and the post-operative incision scar was acceptable cosmetically. 3. The limitation of the joint motion did not remain due to early exercise post-operatively. 4. The complications such as infection, neurovascular injury, scuffing of joint cartilage, etc. could be avoided.