To investigate the effects of gastric bypass surgery(GBP) on hepatic phosphoenolpyruvate carboxykinase(PEPCK) mRNA expression in type 2 diabetic Goto-Kakizaki rats. Male GK rats were randomized into three groups: gastric bypass surgery(n=10), sham operation with diet restriction(n=10), and sham operation alone(n=10). Liver specimens of GK rats were collected during the intraoperative period for self-control study and 8 weeks after surgery. Fasting blood glucose, food intake, and body weight were recorded before surgery and 1, 2, 4, 8 weeks after surgery. The expression of PEPCK mRNA was measured by real-time PCR. The fasting plasma glucose level decreased from(17.6±2.1) mmol/L before surgery to(7.5±0.9) mmol/L 8 weeks after surgery in GBP group. The level of PEPCK mRNA decreased from 1.08±0.38 before surgery to 0.41±0.10 8 weeks after surgery, significantly lower than that in sham operation alone group(1.04±0.12)(P<0.01). The level of PEPCK mRNA in diet restriction group increased from 1.15±0.16 before surgery to 2.54±0.82 8 weeks after surgery(P<0.01). The expression of PEPCK mRNA in diet restriction was significantly higher than that in CBP group(P<0.01). GBP can significantly improve hyperglycemia in type 2 diabetic GK rat models, which may be associated with the decrease of hepatic PEPCK mRNA level.