We dissected 105 cadaveric shoulders to study the origin of the tendon of the long head of biceps, and examined histologically the interrelationship between the tendon, the supraglenoid tubercle and the superior labrum of the glenoid. In all specimens approximately 50% of the biceps tendon arose directly from the superior glenoid labrum with the remainder attached to the supraglenoid tubercle. The main labral origin was from the posterior labrum in more than half of the specimens, and in a quarter this was the only labral attachment. On the basis of the biceps attachment to the anterior or posterior labrum, we distinguished four types of origin. These normal anatomical variations are significant for arthroscopic diagnosis and may help to explain the various patterns of injury seen in partial or complete detachment of the tendon, the labrum or both.