OBJECTIVE To investigate splanchnic blood flow changes in patients with hepatic cirrhosis and portal hypertension. METHODS Duplex Doppler ultrasound (US) was used to measure blood flow in the superior mesenteric artery (SMA) and splenic artery in 20 patients with biopsy-proved cirrhosis and clinical evidence of portal hypertension, and in 20 healthy volunteers who were matched for age and sex. RESULTS Mean SMA and splenic artery blood flow was significantly greater in the patients than in healthy subjects. Neither SMA nor splenic artery blood flow was increased in patients with normal-sized spleens; however, blood flow was significantly elevated in patients with splenomegaly. Total splanchnic blood flow in patients was also significantly elevated compared with healthy subjects. Total splanchnic blood flow in patients with normal-sized spleens was not significantly elevated compared with healthy subjects, but splanchnic flow was significantly increased in patients with splenomegaly. CONCLUSIONS Blood flow is increased in the SMAs and splenic arteries of patients with cirrhosis and portal hypertension. Increased splanchnic blood flow associated with cirrhosis may occur exclusively in patients with splenomegaly.