Quantitative descriptions of the attachment sites of the main posterolateral knee structures have not been performed. To qualitatively and quantitatively determine the anatomic attachment sites of these structures and their relationships to pertinent bony landmarks. Cadaveric study. Dissections were performed and measurements taken on 10 nonpaired fresh-frozen cadaveric knees. The fibular collateral ligament had an average femoral attachment slightly proximal (1.4 mm) and posterior (3.1 mm) to the lateral epicondyle. Distally, it attached 8.2 mm posterior to the anterior aspect of the fibular head. The popliteus tendon had a constant broad-based femoral attachment at the most proximal and anterior fifth of the popliteal sulcus. The popliteus tendon attachment on the femur was always anterior to the fibular collateral ligament. The average distance between the femoral attachments of the popliteus tendon and fibular collateral ligament was 18.5 mm. The popliteofibular ligament had two divisions-anterior and posterior-in all cases. The average attachment of the posterior division was 1.6 mm distal to the posteromedial aspect of the tip of the fibular styloid process and the anterior division attached 2.8 mm distal to the anteromedial aspect of the tip of the fibular styloid process. These structures had a consistent attachment pattern. This information will prove useful in the study of anatomic repair and reconstruction of the posterolateral structures of the knee.