An increase in splanchnic blood flow in both arterial and venous beds has been demonstrated in inflammatory bowel disease (IBD) by means of angiographic and scintigraphic studies. Doppler ultrasound (US) enables a non-invasive evaluation of splanchnic arterial inflow in the superior mesenteric artery (SMA) and of venous outflow in the portal vein. The aim of this study was to assess the role of Doppler US in detecting changes in the hemodynamic variables measured in patients with IBD. Forty-five patients with IBD were studied, including 22 with Crohn's disease (CD) and 23 with ulcerative colitis (UC), and compared with 45 matched normal subjects. The mean velocity of portal flow (Vmean) and the resistance index (RI) of the SMA were evaluated by Doppler US. In CD the Vmean of portal flow was significantly higher in patients with active disease than in controls (p less than 0.001) and patients with inactive disease (p less than 0.001). The RI of the SMA was significantly lower in active disease than in controls (p less than 0.005), but no significant difference was noted between active and inactive CD. Also in UC, the Vmean of portal flow was significantly higher in patients with active disease than in controls (p less than 0.01) and patients with inactive disease (p less than 0.05). The RI of the SMA was significantly lower in active disease than in controls (p less than 0.005) and in patients with inactive disease (p less than 0.005). Doppler follow-up studies were carried out in 10 patients after initiation of treatment.(ABSTRACT TRUNCATED AT 250 WORDS)