This study evaluated the role of duplex Doppler sonography in the diagnosis of VOD of the liver after bone marrow transplantation. Sixteen patients with clinical criteria of VOD were studied. The final diagnosis was achieved by transjugular liver biopsy, and the hepatic venous pressure gradient was measured during the procedure to estimate portal pressure. Nine patients (56.2%) had histologically proved VOD. Gallbladder wall thickening was present in 75% of patients with VOD, but in none of those without it (P = 0.01). Gallbladder wall thickening and ascites were present only in patients with portal hypertension. Nine patients (five with VOD and four without it) also were evaluated with duplex Doppler sonography, and no obvious flow abnormalities were detected in the portal vein and hepatic veins. These results suggest that sonography is useful in detecting early signs of portal hypertension pointing to the diagnosis of VOD in patients with bone marrow transplantation.