For fifty-five patients with acute low-back pain or radicular pain, ascending lumbar venography was as accurate as myelography (86 per cent) in localized herniation of a lumbar disc in surgically proved cases. Myelography and lumbar venography are complementary diagnostic studies which should be used together in doubtful cases. Lumbar venography is easily performed is well-tolerated, and is relatively painless. It is not associated with arachnoiditis and has a negligible complication rate.