We studied the gross and histologic anatomic characteristics of the lateral collateral ligament complex of the elbow joint from 15 cadavers to demonstrate its cross-sectional anatomy. The lateral ulnar collateral ligament adheres closely to the supinator, the extensor muscles, its intermuscular fascia, and the anconeus muscle and lies posterior to the radial collateral ligament. The lateral ulnar collateral ligament itself was identified with microscopy as a slender, poor structure consisting of the thick area of the posterolateral capsuloligamentous layer and a poorer structure than the anterior bundle of the medial collateral ligament as the primary stabilizer of the elbow joint. We believe that the lateral ulnar collateral ligament contributes to rather than is a major constraint to the posterolateral rotatory instability as part of the lateral collateral ligament complex with the surrounding tissues.