Abstract: OBJECTIVE To observe the hypoglycemic effect and mechanism of endive decoction on streptozotocin induced diabetic rats. METHODS The diabetic rat model was established by intraperitoneal injection of streptozotocin. Rats were divided into normal group, control group, melbine group (0.47 g·kg^-1), endive decoction high, middle and low dose (3.34, 1.67, 0.83 g·kg^-1) group. The blood glucose was monitored and the activity of serum superoxide dismutase(SOD), the level of malondialdehyde(MDA), glutathione (GSH) and nitric oxide (NO), cholesterol(TC), low density lipoprotein(LDL), high density lipoprotein protein(HDL), triglyceride(TG), glycosylated serum protein(GSP), insulin (INS), insulin antibody(IAA) and the activity of nitric oxide synthase(NOS) was detected in each group. Pathological changes of pancreas and kidney in rats were observed by HE staining. RESULTS Compared with the blank group, the blood sugar, serum levels of MDA, NO, TC, LDL, TG, GSP, IAA and activity of NOS in the model group increased significantly(P<0.01), while the activity of SOD, level of GSH, HDL and INS decreased significantly(P<0.01). Compared with model group, melbine group and each dose of endive decoction groups could reduce blood sugar level in varying degrees. Melbine group and endive decoction high dose group could significantly increase SOD, GSH, HDL, INS level(P<0.01), significantly reduce NOS activity, MDA, NO, TC, LDL, TG, GSP, IAA level(P<0.01 or P<0.05), and improve pathological changes of pancreas and kidney. CONCLUSION Endive decoction has hypoglycemic effect. The mechanism of action is related to the promotion of insulin release from pancreatic β cells, and repair the islet cells, protect the kidney tissue.