Paralleling the rise in the incidence of obesity and diabetes worldwide, nonalcoholic fatty liver disease (NAFLD) is being increasingly recognized as one of the major causes of chronic liver disease. Doppler sonography is used as a diagnostic method in the non-invasive assessment of the hemodynamics of hepatic vascular flow in liver diseases. We investigated the effects of fatty infiltration in the liver on the Doppler flow hemodynamics of the portal vein. Doppler sonography of the liver and portal vein was performed in 60 subjects with NAFLD and 20 healthy volunteers (control). The patients were grouped into mild (grade 1), moderate (grade 2), and severe (grade 3) according to sonographic appearance of hepatosteatosis (n = 20 for each group). The vein pulsatility index (VPI), mean flow velocity (MFV), peak maximum velocity (V_max), and peak minimum velocity (V_min) of the portal vein were significantly lower in patients with NAFLD than those of the controls (p < 0.001). The VPI was 0.20 in the patients and 0.31 in the control. The MFV was 12.3 cm/sec in the patients and 16.5 cm/sec in the control group. The portal vein flow was found to be decreased as the grade of fatty infiltration increased for VPI (r = −0.946, p < 0.001), MFV (r = −0.951, p < 0.001). The alteration in Doppler waveform pattern of portal vein with fatty liver population suggests reduced vascular compliance in the liver.