Lumbar epidural venography performed in 107 patients with normal or nondiagnostic myelograms resulted in correct preoperative diagnosis in 25 of 27 patients (92%) with herniated disc disease and three of six patients (50%) with nerve root compression without associated disc herniation. Compression or occlusion of an epidural and/or radicular vein at the disc level is the most significant venographic abnormality. Potentially confusing venographic findings such as flow defects, extravertebral veins mimicking epidural veins, and occlusion of radicular veins by the catheter must be recognized to prevent false diagnoses. Lumbar epidural venography is valuable for the diagnoses of herniated lumbar discs not demonstrated by myelography.