Monocyte-chemotactic-protein-1 (MCP-1) plays vital roles in immune response, angiogenesis, and pregnancy outcome. We investigated plasma MCP-1 concentrations in 40 mothers and their 20 intrauterine-growth-restricted (IUGR) and 20 appropriate-for-gestational-age (AGA) fetuses and neonates on postnatal days 1 (N1) and 4 (N4). Maternal and fetal MCP-1 concentrations were decreased (P<001 and P = .018, resp.), whereas N1 MCP-1 concentrations were elevated in IUGR group (P = .012). In both groups, fetal MCP-1 concentrations were lower compared to N1 and N4 ones (P = .045, P = .012, resp., for AGA, P< .001 in each case for IUGR). Reduced maternal and fetal MCP-1 concentrations in IUGR may reflect failure of trophoblast invasion, suggesting that down-regulation of MCP-1 may be involved in the pathogenesis of IUGR. Increased MCP-1 concentrations in IUGR neonates and higher postnatal ones in all infants may be attributed to gradual initiation of ex utero angiogenesis, which is possibly enhanced in IUGR.