This study was designed to investigate the utility of color Doppler sonography in the evaluation of portosystemic shunts. Thirty-one patients with a total of 32 shunts were imaged. The types of shunts examined included portacaval, five; mesocaval, eight; distal splenorenal (Warren), 14; and mesoatrial, five. Sonography was performed without knowledge of the status of the shunt, although the type of shunt was known before beginning the study. The sonographic studies were evaluated to determine their sensitivity and specificity on the basis of a prospective comparison with angiography or MR imaging (22 cases). The possible advantages of color Doppler over duplex Doppler sonography in evaluating portosystemic shunts were also investigated, as was the ability of color Doppler sonography to image specifically the shunt anastomoses. Color Doppler sonography successfully inferred shunt patency (17 cases) or thrombosis (five cases) in all 22 shunts for which correlative imaging was available (sensitivity = 100%, specificity = 100%). In comparing duplex with color Doppler sonography in all 32 shunts, the two techniques were almost equally effective in establishing patency in portacaval, mesocaval, and mesoatrial shunts. Duplex Doppler sonography, however, provided useful diagnostic information in only four of 14 splenorenal shunts. Color Doppler correctly inferred patency or thrombosis in all 14. Among all 32 shunts, the anastomosis was shown clearly by color Doppler in 23, probably in four, and not at all in five. Our results suggest that color Doppler sonography is an excellent method for the evaluation of all varieties of surgically created portosystemic shunts. In particular, color Doppler sonography appears to be superior to duplex Doppler sonography in imaging splenorenal communications.