Intensive local leukocyte infiltration in the uterine cervix is a characteristic feature in the process of cervical ripening. The infiltrated leukocytes include neutrophils, macrophages and monocytes, which are believed to play important roles in cervical ripening by secreting elastase, matrix metalloproteinase and interleukin-1 (IL-1). Interleukin-8 (IL-8) and monocyte chemotactic protein-3 (MCP-3) belong to the CXC and CC chemokine families, and mediate the chemotaxis of neutrophils and monocytes/macrophages respectively. The aim of the present study was to investigate the possible involvement of IL-8 and MCP-3 in leukocyte chemotaxis in cervical ripening. Immunohistochemistry and RT-PCR detected both IL-8 and MCP-3 expression in human pregnant uterine cervices. Labour-like cyclic mechanical stretch for 48 h significantly elevated both IL-8 (555%) and MCP-3 (360%) secretion from cultured human uterine cervical fibroblast (CxF) cells (P<0.05 for both). Cyclic mechanical stretch for 24, 36 and 48 h significantly increased both IL-8 and MCP-3 mRNA expression in CxF cells (P<0.05 for all). The stretch-induced augmentation of both IL-8 and MCP-3 expression was significantly suppressed by an activator protein-1 (AP-1) inhibitor, curcumin. These data suggest that cyclic mechanical stretch of the uterine cervix by the presenting part of the fetus during labour may augment both IL-8 and MCP-3 production in the uterine cervix via AP-1 activation.