Degenerative rotator cuff tendon disease (tendinopathy) is the most common disorder of the shoulder. A full-thickness tear of the rotator cuff may be caused by degeneration, or it may develop due to an acute trauma. The typical symptoms include pain and functional deficiencies. Diagnostics is based on clinical findings. The primary radiologic imaging is x-ray. Degenerative tendon diseases are primarily treated conservatively in primary health care, the most important treatment modality is physiotherapy-guided therapeutic rehabilitation. Surgical treatment is considered in full-thickness rotator cuff tears, especially after traumatic onset.