Granulocyte colony-sitmulating factor (G-CSF ; normal range < 30 pg/ml) is a cytokine that stimulates the proliferation and activation of neutrophils. In this study, we investigated changes in the plasma G-CSF level after gastrointestinal surgery. The subjects were 23 patients undergoing subtotal esophagectomy (Group E, n = 8), pancreaticoduodenectomy (Group P, n = 5), radical total gastrectomy (Group G, n = 5), or cholecystectomy (Group C, n = 5). In addition to G-CSF, duration of surgery, transfused fluid volume, C-reactive protein (CRP) concentration and neutrophil counts were recorded. G-CSF levels just after surgery were 3,301±2,130 pg/ml (mean ±SD), 1,442±180 pg/ml, 941 ±538 pg/ml, and 111±73pg/ml for patients in proups E, P, G and C, respectively. G-CSF levels were correlated with postoperative maximum CRP, the duration of surgery and the transfused fluid volume during the operation. The results show that extensive surgical procedures are associated with higher postoperative plasma G-CSF levels, suggesting that the increase in plasma G-CSF may be due to activation of the host defense in response to surgical stress.