PURPOSE: The purpose of this study is to assess the usefulness of Doppler parameters in transplanted kidney function. MATERIALS AND METHODS: Doppler parameters, including resistive index (RI), pulsatility index (PI), peak systolic velocity (PSV), and end diastolic velocity (EDV) were measured in the interlobar artery of 55 transplant recipients. Patients were grouped according to glomerular filtration rate (GFR): Group A (GFR < 30 ml / min / 1.73 m2, n = 27) and group B (GFR > or = 30 ml / min / 1.73 m2, n = 28). Doppler parameters were compared between groups and correlated with the GFR. RESULTS: GFR (40.1 +/- 26.9) showed a significant negative correlation with RI (0.69 +/- .08) (p = .002, r = -.414). RI (0.72 vs. 0.67), PI (1.42 vs. 1.23), and EDV (10.5 vs. 15.3) differed significantly between groups (p < .05), however, PSV was not (36.9 vs. 47.1). Patients in group A (n = 11) with a lower RI than the mean had significantly lower PSV (31.7 vs. 45.1; p = .027) and EDV (11.1 vs. 16.7; p = .017), compared with such patients in group B (n = 21). CONCLUSIONS: Doppler parameters are useful for evaluation of function of transplanted kidney. Even if the RI is normal, PSV and EDV may be used as hemodynamic indicators.