Objective To investigate the protective effects of G CSF on lungs of rats with acute cholangitis and changes in blood TNF and TXA 2/PGI 2 by treating the rats with G CSF. Methods Seventy two Wistar rats were randomized into the control, infected and treated groups. We established the model of cholangitis in the rats with injection of E. coli 25922 into the bile duct. The animals in the treated group were pretreated with G CSF 500 ng/day bid) for 5 days before the E. coli injection. The levels of blood TNF and TXA 2/PGI 2 were measured at the 3rd, 6th and 12th h after the injection. Meanwhile, the morphological changes in lungs of the rats were observed. Results The morphological changes in lungs were milder and levels of blood TNF and TXA 2/PGI 2 were significantly lower in the treated group than in the infected one (P