On the basis that vasoconstriction may contribute to restenosis following angioplasty, the influence of lumbar sympathectomy on the morphometry of femoral arteries after balloon injury was examined in a pig model. Twenty-six juvenile pigs underwent balloon de-endothelialization of the right femoral artery followed by an open bilateral lumbar sympathectomy (n = 14) or a sham sympathectomy (n = 12). Four weeks later flow was measured in femoral arteries. Animals were then killed and the femoral arteries were perfusion-fixed and harvested. Sympathectomy resulted in a significant (P = 0.04) increase in flow in both the injured (right) and uninjured (left) femoral arteries. Sympathectomy did not inhibit intimal thickening following balloon injury: median (interquartile range) intimal area was 0.4 mm(2) (0.3-0.9) in the sympathectomy group versus 0.5 mm(2) (0.4-0.9) in the sham group. Sympathectomy did, however, result in a significant (P = 0.02) increase in the lumen area: 1.1 mm(2) (0.8-1.8) versus 0.7 mm(2) (0.6-0.9). Sympathectomy may reduce vasospasm following angioplasty with the potential for clinical benefit. (C) 1999 The International Society for Cardiovascular Surgery, Published by Elsevier Science Ltd. All rights reserved.