The aim of this study was a prospective search for splenoportal venous obstruction (SPVO) in a medical-surgical series of 266 patients with chronic pancreatitis who were followed up a mean time of 8.2 years. SPVO was systematically searched for using ultrasonography and then confirmed by angiography or computed tomography. SPVO was found in 35 patients (13.2%) but was symptomatic in only two. Initial obstruction involved the splenic vein in 22 patients, the portal vein in 10, and the superior mesenteric vein in three. Since venous obstruction extended from the splenic to the portal vein in five patients, the prevalence of portal obstruction was 5.6% (15/266). Acute pancreatitis and pseudocysts were the probable cause of SPVO in 91.4% of our cases. Half the cases of splenic venous obstruction were related to pseudocysts of the caudal pancreas. Esophageal varices were found in two patients and gastric varices in four at the time of diagnosis and during follow-up. At the end of follow-up, 12 patients had undergone splenopancreatectomy (N = 11) or splenectomy (N = 1). Only one patient was operated on for massive esophageal variceal bleeding, and another patient died due to intractable colic variceal bleeding. In four of six patients operated on with portal vein obstruction, surgery was difficult due to venous collaterals. Ten patients were not operated on and 13 patients operated on were not treated for SPVO. The mean follow-up after diagnosis of SPVO for these final 23 patients was 28.9 months. None of these patients bled.(ABSTRACT TRUNCATED AT 250 WORDS)