Idiopathic portal hypertension (IPH) is a rare and complex disorder characterized by portal hypertension in the absence of cirrhosis or extrahepatic portal vein obstruction. This chapter provides a comprehensive overview of IPH, covering its etiology, epidemiology, clinical manifestations, pathology, and imaging features. While the exact cause remains unclear, various factors including toxic substances, infections, and immune abnormalities are implicated. IPH predominantly affects young to middle-aged individuals, with a higher incidence in developing countries. Clinical presentations typically involve splenomegaly, anemia, and complications of portal hypertension, such as variceal bleeding. The chapter emphasizes the crucial role of imaging in diagnosis, detailing characteristic findings across various modalities including angiography, computed tomography (CT), magnetic resonance imaging (MRI), and ultrasound. Key imaging features include signs of portal hypertension, acceptable liver volume, and specific vascular changes like portal vein wall thickening and cavernous transformation. Diagnostic challenges are addressed, offering guidance on differentiating IPH from other causes of portal hypertension. The chapter also highlights the importance of liver biopsy in confirming the diagnosis. A case study is presented, demonstrating the practical application of imaging in IPH diagnosis. The teaching points underscore the rarity of IPH, its potential for misdiagnosis, and the critical importance of a comprehensive diagnostic approach combining clinical, laboratory, and imaging findings.