Epidural double-catheter venography may be considered as a most reliable method of demonstrating lumbar disc herniation. In our case material the diagnostic results proved to be more accurate than the results of lumbar myelography, especially when very lateral disc herniations are concerned. In the operated patients the diagnostic accuracy of the venograms was 94% versus a myelographic accuracy of 85%. Systematic use of two catheters and simultaneous contrast injection provides the possibility to obtain homogeneous filling and excellent opacification of the anterior epidural veins at any lumbar level. During the procedure a choice can be made out of over 20 catheter position combinations to obtain good quality venograms. In 40 patients metrizamide (Amipaque) is used as a contrast agent in an iodine concentration of 350--370 mg/ml. This concentration does improve the opacification of the epidural venous plexus, providing better diagnostic information. Metrizamide causes hardly any discomfort to the patient, even when 50--70 ml are injected within 5 sec.