Tendinopathy of the long head of the biceps (LHB) tendon commonly occurs in patients with rotator cuff tears, and the inflammation of one head tends to lead to inflammation of the other. Many theories have been proposed regarding the function of the LHB tendon; however, its exact purpose is poorly understood. It has been described as an important stabilizer of the glenohumeral joint, a depressor of the humeral head, and as a vestigial structure. The LHB tendon can be a significant source of pain in patients with rotator cuff tears. The appropriate treatment depends on the patient's age, comorbidities, activity level, extent of disability, the presence of rotator cuff arthropathy, and the quality of the rotator cuff tissue. Conservative treatment is usually attempted first, with modalities such as nonsteroidal anti-inflammatory drugs, corticosteroid injections, physical therapy, and activity modification. If symptoms persist, biceps tenotomy or tenodesis may be combined with rotator cuff repair, depending on the quality of the rotator cuff tissue, the severity of rotator cuff arthropathy, and the willingness of the patient to comply with postoperative immobilization and rehabilitation. Even when rotator cuff repair is not possible, isolated tenotomy or tenodesis of the LHB tendon can provide substantial pain relief.