The authors have performed lumbar venography on 120 occasions in patients with low back pain. In 58 patients in whom the herniated disc was confirmed, the result of venography was positive and the localisation was precise in 67 cases. It is concluded that the method is safe, reliable and allows precision in diagnosis to allow better selection for surgical treatment. The examination is particularly useful in recurrent sciatica, fractures of the lumbar spine, recent or old, and in spinal stenosis. It may be associated with discography when the result is not clear cut.