The vasoreactivity and thrombogenicity of laser‐thermal angioplasty were examined and compared with those of balloon angioplasty in an atherosclerotic rabbit iliac artery. Eight rabbits underwent laser‐thermal angioplasty with a 1.7‐mm hot‐tip probe activated at 7 W with a probe temperature of 126 ± 19°C in one iliac artery. The other iliac artery was treated with balloon angioplasty irsing a 2.0mm balloon. Angiographic luminal diameter increased from 0.19 ± 0.15 to 1.54 ± 0.35 mm by laser and from 0.29 ± 0.22 to 1.84 ± 0.20 mm by balloon (P<0.0001. respectively). However, it decreased to 1.34 ± 0.42 for laser and 0.45 ± 0.39 for balloon 60 minutes later (P<0.0001 vs immediately post). Both iliac arteries were visualized using angioscopy, which revealed thrombotic obstruction of 91% stenosis in the ballooned artery and 8% stenosis in the lased artery. Vasoreactivity of treated vessels was also investigated. Segments 3‐mm long were obtained from either treated artery or control artery and examined for noradrenaline (10−7M) contraction. The segments were then mounted isotnetrically with 1 g tension in Krebs‐bicarbonate buffer. Developed tension was 0.13 ± 0.21 g for laser thermal and 2.33 ± 0.4 g for its control (P<0.0001), and 0.15 ± 0.16 g for balloon dilatation and 2.12 ± 0.43 g for its control (P<0.0001). Neither acetylcholine at 10−6M or papaverine at 10−4M induced relaxation of treated segments. Histology showed slight thermal injury at thermally‐treated sites without thrombus, and intimal and medial dissection with thrombus formation at balloon dilated site. In conclusion: (1) neither a laser‐thermal recanalized or a balloon dilated obstructed artery is vasoreactive to constrictive or relaxant agents; and (2) laser‐thermal angioplase results in less thrombogenicity than balloon angioplas