In a prospective, consecutive study we determined the frequency of common symptoms and signs in 300 patients with lumbar nerve-root compression syndromes. We compared 100 patients with disc herniation (mean age 43 years), 100 with lataral spinal stenosis (41 years) and 100 with central spinal stenosis (65 years), using a standard protocol of common signs and symptoms. The diagnoses were established by one or more of myelography, CT, MRI and nerve-root block, and all were confirmed at operation. The preoperative duration of symptoms was significantly shorter in patients with disc herniation. Pain at rest, at night, and on coughing was as common in lateral stenosis as in disc herniation, but regular consumption of analgesics was more common in patients with disc herniation. Positive straight-leg-raising tests were more common in disc herniation than in lateral stenosis and were uncommon in central stenosis. Motor disturbances were seen most often in central spinal stenosis, especially patellar reflex changes. Sensory disturbances were most common in patients with complete disc herniation.