Endofibrosis (EF) of the iliac arteries is a flow-limiting condition typically seen in highly trained endurance athletes. Thirty-seven athletes (74 limbs) were referred to our department with suspected EF. All patients had a pre- and postexercise color Doppler ultrasound (CDU) of the iliac arteries. Doppler waveform and peak systolic velocity (PSV) and end-diastolic velocity (EDV) were assessed pre- and postexercise. Endofibrosis was diagnosed with CDU in 24 athletes (29 limbs). Arterial wall and course abnormalities were detected at rest in 20 (67%) symptomatic limbs of athletes with and 4 (22%) symptomatic limbs of athletes without EF. Postexercise abnormal waveforms of the stenotic/damped type were seen in the iliac arteries in all 29 limbs of athletes diagnosed with EF. These waveform changes were accompanied by high PSV (>350 cm/s) and EDV (>150 cm/s), with (n = 10; 34%) or without (n = 19; 66%) the evidence of reduced arterial lumen caliber. Color Doppler ultrasound can be used to detect EF.