The significance of the physical examination is controversial since Slocum and Larson first described the concept of rotatory instability of the knee. The findings of the physical examination of the 101 knees of 95 patients from 1982 to 1985 were compared with the operative findings. The results were as follows. 1. Valgus stress test a) The valgus stress test c the knee in extension was positive in 1) combined tear of medial collateral ligament, posterior oblique ligament, either anterior or posterior cruciate ligament, 2) avulsion fracture of medial collateral ligament and 3) extensive tear of medial capsular ligament. But the test was negative when the posterior oblique ligament was intact although the medial collateral ligament and the anterior cruciate ligament were torn. b) The valgus stress test c the knee in 30° flexion was positive in all cases of torn medial collateral ligament, But it was severer in cases of positive test in full extension. 2. The varus stress test in extension was positive when the anterior or posterior cruciate ligament was torn in addition to lateral collateral ligament and posterolateral capsule. 3. The Slocum test was negative, or positive only in neutral rotation in isolated tear of the anterior cruciate ligament. 4. The Ritchey-Lachman test was positive in all cases of torn anterior cruciate ligament. 5. The posterior drawer test could be positive in cases of intact posterior cruciate ligament. 6. The pivot shift test was negative in cases of torn medial collateral ligament and posterior oblique ligament although there was associated tear of the anterior cruciate ligament. 7. The flexion rotation drawer test was positive in all cases of torn anterior cruciate ligament although there was associated tear of the medial collateral ligament. The positive test didn’t always mean anterolateral rotatory instability, 8. The reversed pivot shift test was positive in cases of posterolateral rotatory instability but it was negative in cases of associated tear of posteromedial capsule. 9. The drawback of external rotation drawer test was that it depended on subjective evaluation. 10. The rotation test was very good for the rotatory instability but it could not be used in bilateral injury and the anterolateral rotatory instability of isolated tear of anterior cruciate ligament.