AIM To investigate the effects of sinusoidal endothelial cell (SEC) conditioned medium on the expression ofconnective tissue growth factor (CTGF) in rat hepatic stellate cells (HSC).METHODS By in situ collagenase perfusion and two-step Percoll gradient centrifugation, SECs wereisolated and cultured from normally and CCl4-treated Wistar rats, and the SEC conditioned media werecollected. HSCs were prepared from Wistar rats by in situ perfusion and single-step Nycodenz gradient, andwere cultured with SEC conditioned media. Expression of CTGF in HSC was assessed using reversetranscription-polymerase chain reaction (RT-PCR).RESULTS Expression of CTGF was not found in freshly isolated HSC and in primary culture of HSC onday 4 with SEC conditioned media from normal rats, but was present in primary culture of HSC on day 4 withSEC conditioned media from CCl4-induced liver fibrosis rats. Expression of CTGF was observed in culture-activated HSCs, and the effect of SEC conditioned media from CCl4-induced liver fibrosis rats on theexpression of CTGF gene in activated HSCs was not significant.CONCLUSION Expression of CTGF might be relative to the activation of HSC and the liver fibrogenesis,and damaged SECs play a very important role in the early stage of activation of HSC.