The plasma concentration of monocyte chemoattractant protein-1 (MCP-1) antigen is higher in patients with restenosis after coronary angioplasty than in those who do not restenose. In this study the MCP-1 expression of coronary atherectomy specimens was investigated by immunohistochemistry. Samples were obtained from 12 patients with restenosis and 15 with de novo lesions by directional coronary atherectomy. MCP-1 immunoreactivity was found in all patients in the restenosis group and in 8 of the de novo group. The frequency of macrophage expression was higher in the restenosis group than in de novo group. These results indicate that local expression of MCP-1 may be associated with the mechanisms of vascular remodeling after coronary angioplasty.