Sinistral (left-sided) portal hypertension. Between 1953 and 1988, 21 patients with splenic vein thrombosis (SVT), 12 of whom had sinistral portal hypertension (SPH) were treated at our institution. SVT was identified at autopsy in nine patients. Twelve additional patients presented with SPH: bleeding esophageal varices, SVT and normal hepatic function. SVT was caused by pancreatic neoplasm (5), chronic pancreatitis (5), and pancreatic pseudocyst (2). SVT was diagnosed by splanchnic angiography, splenoportography, computerized tomography, and ultrasonography. Gastric varices were diagnosed by endoscopy (10) and barium swallow (2). Splenectomy was performed as primary therapy in 10 patients. Three of these 10 had en block distal pancreatectomy. Two high-risk patients had splenic artery embolization, one as a prelude to splenectomy performed 48 hours later and the other as definitive therapy. One splenectomized patient continued to bleed. No further bleeding occurred in 10 splenectomized patients in follow-up from 1 week to 14 years. Sinistral portal hypertension is a clinical syndrome of splenic vein thrombosis caused by pancreatic pathology and manifests as bleeding gastric varices in patients with a patent portal vein and normal hepatic function. Splanchnic arteriography is necessary for accurate diagnosis. Splenectomy is the effective treatment of choice. 