The clinical features of 86 cases of idiopathic portal hypertension, the equivalent of hepatoportal sclerosis in the United States and of noncirrhotic portal fibrosis in India, are presented. This disease is characterized by overt splenomegaly with pancytopenia, portal hypertension, and relatively mild abnormalities in liver function tests. Although differential diagnosis from liver cirrhosis is not always easy, liver histology, laparoscopy, portography, hepatic venography, and measurement of wedged hepatic vein pressure are useful in diagnosis. Prognosis is relatively benign if variceal bleeding is controlled or prevented, and the disease does not progress to cirrhosis. The etiology is still undetermined, but the liver pathology characterized by occlusive changes of the intrahepatic portal radicles, portal and periportal fibrosis, and irregularly distributed parenchymal atrophies suggests some sort of portal venopathy that causes decreased portal perfusion of peripheral liver parenchyma. These patients with idiopathic portal hypertension were compared with 63 cases of cirrhosis with splenomegaly and 80 cases of cirrhosis without splenomegaly. There was some similarity in hematologic findings between idiopathic portal hypertension and cirrhosis with splenomegaly, but the basic disease process seemed distinctly different. The cause of marked splenomegaly does not seem to be simply congestion, and remains an enigma.