Objective: The aim of this study was to investigate the hemodynamics of cavernous transformation of the portal vein (CTPV) using color Doppler sonography and to correlate it with sonographic findings and clinical manifestations. Methods: Using color Doppler sonography, we studied 25 patients who satisfied the sonographic diagnostic triad of CTPV and compared clinical, sonographic, and color Doppler findings. We also compared the hemodynamics of the liver vasculature in a group of CTPV patients with that in a group of normal subjects. Results: We could differentiate five cases of dilated hepatic artery without formation of CTPV from 20 cases of CTPV. In 13 cases of CTPV, the cause of the portal vein thrombosis prior to CTPV could be determined. Two types of CTPV were distinguished: linear type (small diameter without tortuosity) and tortuous type (large diameter with tortuosity). There were no particular tendencies in the cause or distribution between the two groups, but the flow velocity was significantly higher in the tortuous type than in the linear type. Slow continuous flow with little or no respiratory variations was observed in CTPV by color Doppler sonography in agreement with previous reports, and the velocity of CTPV was slower than that of the portal flow in normal subjects. The flow velocity was not related to the cause or the presence of developed collaterals, and the flow direction was always hepatopetal. Conclusion: Color Doppler sonography was considered to be the most useful modality for the diagnosis and comprehension of the hemodynamics of CTPV.