The study was planned to evaluate renal vascular resistance by means of duplex Doppler ultrasonography in patients with progressive systemic sclerosis (PSS) with or without signs of renal involvement. Twenty-two female patients with PSS (mean age 38.5 +/- 17.3 years) and 20 age-matched (mean age 36.7 +/- 7.2 years) female healthy controls participated to the study. Doppler indices of renal vascular resistance--resistive index (RI), pulsative index (PI), and systolic-to-diastolic flow velocities ratio (S/D ratio)--were determined on main renal artery and interlobar artery. RI, PI and S/D ratio were found to be increased in PSS patients with signs of renal involvement as compared to those without renal manifestations and healthy controls (p<0.0001 for all groups). Doppler indices of renal vascular resistance were closely related to the duration of the disease, age, and plasma renin activity. Doppler ultrasound is a useful and informative technique in the monitoring of PSS patients with renal involvement.