The computed tomographic (CT) findings in 18 patients with angiographically proved, isolated splenic vein occlusion (SVO) were retrospectively analyzed. The distribution of venous collateral vessels and the frequency of their occurrence in these patients were then compared with CT findings in 17 patients with proved portal hypertension and normal CT findings in 20 patients. Short gastric and coronary collateral vessels were seen in 61% and 83%, respectively, of patients with SVO and in 71% each in patients with portal hypertension. However, a large gastroepiploic vein was seen only in patients with SVO (11 of 18 patients [61%]). Recanalization of umbilical/paraumbilical veins was seen only in patients with portal hypertension (seven of 17 patients [41%]). Results suggest that collateral vessels in SVO often have a characteristic and distinctive appearance on abdominal CT scans.