Optimal evaluation of experimental angioplasty procedures would allow real-time simultaneous assessment during the procedure without direct manipulation of treated arterial segments. To assess the feasibility and utility of transvenous real-time intravascular ultrasound imaging during experimental angioplasty, 11 consecutive atherosclerotic iliac artery segments in rabbits were imaged before, during and after thermal or conventional perfusion balloon angioplasty. A 20-MHz intravascular ultrasound catheter was positioned in the adjacent vein, and images were correlated with data from quantitative angiography and histologic studies. Images suitable for analysis were obtained at all 11 sites. Arterial distension and recoil were observed during balloon inflation and deflation. Measurements of lumen diameter and cross-sectional area by intravascular ultrasound and angiography were closely correlated (r2 = 0.90, SEE = 0.2 mm, and r2 = 0.90, SEE = 0.8 mm2, respectively). Intimal dissections were identified in six segments by intravascular ultrasound and all were concordant with histologic findings. Thus, real-time transvenous ultrasound avoids manipulation of the treated artery, and is a feasible modality for dynamic quantitative and qualitative assessment of arterial interventions.