Three hundred and thirty-seven patients with portal hypertension and recurrent bleeding from oesophageal varices were examined by sonography. The situation was correctly elucidated in 17 out of 21 patients (81%) with pre-hepatic blocks, in 275 out of 313 cases (88%) with intra-hepatic blocks and in two out of three cases with post-hepatic blocks. The relevant findings consisted of stenoses and occlusions of the portal venous system and collaterals in pre-hepatic blocks, dilatation of the portal venous system and hepato-fugal collaterals in intra-hepatic blocks and occlusion of the hepatic veins in post-hepatic blocks. Sonography is recommended in cases of portal hypertension because of its non-invasive nature and high accuracy as the primary form of investigation. Spleno-portography should be used only if surgery is indicated.