1. The aim of this study was to evaluate whether caffeic acid phenethyl ester (CAPE), an active component of propolis, was able to reduce neointimal formation in a model of endothelial injury of rat carotid artery (balloon angioplasty). Furthermore, we investigated the relationship between neointima formation and nuclear factor-kappaB (NF-kappaB) activation and we correlated NF-kappaB activation to the expression of inducible isoform of cyclo-oxygenase (COX-2) in injured carotids. 2. In control group a significant proliferation of neointima was observed 14 days after balloon angioplasty, which was correlated to an increase of NF-kappaB/DNA binding activity as well as p50/p65 nuclear levels compared to those observed in the carotids from sham-operated rats. Furthermore, NF-kappaB activation was correlated to increased COX-2, but not beta-actin, protein expression. 3. Treatment of rats for 14 days with CAPE (3, 10, 30 mg x kg(-1)) caused a significant inhibition of all the parameters assayed, except beta-actin protein expression. 4. These results indicate that treatment with CAPE may lead to a reduction of neointima formation by inhibiting NF-kappaB activation and suggest that this agent may have therapeutic relevance for the prevention of human restenosis.