PURPOSE--To verify the minimal proximal and distal residual diameters by quantitative digital angiography and intravascular ultrasound, after the implantation of the intracoronary prosthesis. METHODS--We studied twenty patients with coronary atherosclerosis, ages ranging from 40 to 77 (56.7 +/- 10) years, 13 (65) were male. Patients with eccentric obstructive atherosclerotic lesions of 70 or more in the proximal third of the anterior descendent, circumflex, or right coronary arteries received a stent implant as treatment for the obstruction. RESULTS--The mean proximal minimal residual diameters assessed by digital angiography were 3.32 +/- 0.33 mm and by ultrasound 3.08 +/- 0.31 mm (p < 0.05); the distal diameters by angiography were 3.33 +/- 0.37 mm and by ultrasound 3.05 +/- 0.39 mm (p < 0.05). Therefore, the measurements by ultrasound were always smaller. There is a significant linear correlation between measurements by angiography and ultrasound for both proximal (r = 0.92; p < 0.0001) and distal diameters (r = 0.91; p < 0.0001). The determination coefficient was 84 for proximal diameters and 87 for distal diameters. Therefore, the proximal diameters variate 16 and distal diameters 13 between both methods, due to the peculiarities of each method. CONCLUSION--Both methods correlate adequately, concerning to the measurements; the methods are interdependent, determining with the same accuracy intracoronary diameters in most cases studied; ultrasound is a safe and feasible technical resource for the evaluation of intravascular structures; the intravascular ultrasound system can contribute for the direct analysis inside the vascular structure, immediately after intracoronary stent implanting.