Smooth muscle cell (SMC) migration plays an important role in restenosis after angioplasty, Myosin phosphorylation is necessary for cell migration. Fasudil is an inhibitor of protein kinases, including myosin light chain kinase and Rho associated kinase, thereby inhibiting myosin phosphorylation, and it has been clinically used to prevent vasospasm following subarachnoid hemorrage, Based on these findings, we examined the antimigrative action of fasudil. In SMC (SM-3), fasudil (1-100 mu M) inhibited SMC migration in a dose-dependent man ner (p < 0,001), Fasudil suppressed actin stress fiber formation dose dependently. In rabbit carotid artery, fasudil (10 mg/kg/day) markedly reduced intimal hyperplasia 14 days following balloon injury. Cell kinetic study showed that fasudil did not affect proliferation but enhanced cell loss in the media after injury. We concluded that fasudil reduced neointimal formation after balloon injury through both inhibiting migration and enhancing cell loss of medial SMC. (C) 1999 Academic Press.