To evaluate the incidence of associated glenohumeral lesions in patients with a full-thickness rotator cuff tear, an arthroscopic examination of the glenohumeral joint was performed in 200 shoulders in 195 consecutive patients before arthroscopic rotator cuff repair. One hundred twenty-one (60.5%) had coexisting intraarticular abnormalities. Ninety-six (48%) had minor abnormalities, and 25 patients (12.5%) had major coexisting intraarticular abnormalities. Major lesions (that required operative treatment, changed postoperative rehabilitation, or altered the expected end result) noted at arthroscopic examination were osteoarthritis in nine patients, partial biceps tendon tears in three, labrum tears in three, Bankart lesions in two, superior labrum anterior posterior lesions in five, and glenohumeral synovitis in three patients. Glenohumeral arthroscopy can provide valuable information in patients with a complete rotator cuff tear.