In a prospective study of 163 consecutive patients operated on because they were thought to have lumbar disc hernia, the authors investigated whether physical signs could predict the degree of hernia (complete hernia, incomplete hernia, protruded disc, and normal disc) found at surgery. Stepwise discriminant analysis showed that there were only 2 physical signs of diagnostic value: lumbar range of motion and crossed Lasegue sign. By these signs, 74% of the uncontained hernias and 68% of the contained hernias could be correctly classified. Discrimination also was made between intact annuli (negative exploration and protruded disc) versus ruptured annuli (incomplete hernias and complete hernias). Again, lumbar range of motion and crossed Lasègue sign were the only significant parameters, predicting 71% of the ruptured annuli and 80% of the intact annuli. These 2 physical signs are important because the degree of the hernia is the most important prognostic factor for the outcome of lumbar disc surgery. The degree of the hernia also has an impact on the choice of invasive therapy: open surgery, percutaneous surgery, or enzymatic nucleolysis. Neurologic signs often were absent, showed low correlation to the degree of the hernia, and had a limited value for predicting the level of the hernia. However, they are important for the differential diagnosis in distinguishing between radicular and referred pain.