['To determine whether homocysteine (Hcy) plasma levels are correlated with molecules indicative of endothelial cell and fibroblast activation, including endothelin-1 (ET-1) and monocyte chemoattractant protein-1 and -3 (MCP-1, MCP-3), in patients with systemic sclerosis (SSc).', 'Eighty-two patients were enrolled in this study; the control group included 75 age- and sex-matched subjects. Plasma Hcy was determined by high-performance liquid chromatography; folic acid, and vitamin B(12) plasma levels were determined by a chemiluminescence method. ET-1, MCP-1, and MCP-3 were determined by enzyme-linked immunosorbent assay (ELISA). Analysis of the 677C-->T mutation in the methylenetetrahydrofolate reductase (MTHFR) gene was performed by polymerase chain reaction (PCR) and digestion with the enzyme HinfI.', 'Hcy levels were lower in patients whereas ET-1 was significantly higher in patients and correlated with MCP-1. Stratification of the patients on the basis of Hcy levels was not associated with any statistical difference in the concentration of ET-1, MCP-1, and MCP-3. Patients with diffuse disease presented the highest levels of ET-1 and MCP-1. The distribution of the MTHFR genotypes was not different in patients and controls.'] Do endothelin-1 serum levels correlate with MCP-1 but not with homocysteine plasma concentration in patients with systemic sclerosis?