To determine the role of chemokines in the pathogenesis of systemic sclerosis (SSc), we examined serum levels, spontaneous production by peripheral blood mononuclear cells (PBMC), and histological distribution in the affected skin, of MCP-1, MIP-1α and MIP-1β in SSc patients. Serum levels of these chemokines were examined by ELISA in 58 patients with SSc and 20 normal controls. The levels of these chemokines in culture supernatants from PBMC were also measured by ELISA. Serum levels and spontaneous production levels by PBMC of MCP-1, MIP-1α, and MIP-1β were significantly elevated in patients with SSc compared with normal controls. Elevated serum levels of MCP-1 and MIP-1α significantly correlated with the presence of pulmonary fibrosis. MCP-1 expression in the skin of SSc was immunohistochemically examined using anti-MCP-1 MoAb. MCP-1 was strongly expressed in the epidermis, inflammatory mononuclear cells, and vascular endothelial cells in the sclerotic skin of SSc patients, but not expressed in any control skin. Furthermore, the MCP-1 expression in inflammatory mononuclear cells and endothelial cells significantly correlated with earlier onset of SSc. Thus, MCP-1, MIP-1α and MIP-1β may be involved in the disease process, possibly by augmenting leucocyte migration into the affected tissues in SSc. Furthermore, MCP-1 and MIP-1α may play an important role in the development of pulmonary fibrosis in SSc.