Effects of Mori Folium Ethanol Soluble Fraction (MFESF) on mRNA expression of glucose transporters, acetyl-CoA carboxylase (ACC) and leptin were examined in db/db mice. 500 and 1000mg/kg dose for MFESF (designated by SY 500 and SY 1000, respectively) and 5mg/kg dose for acarbose were administered for 6 weeks. Quantitations of glucose transporters (GLUT-2 and GLUT-4), ACC and leptin mRNA were performed by RT-PCR and in vitro transcription with co-amplification of rat ${eta}$-actin gene as an internal standard. Muscular GLUT-4 mRNA expression in MFESF-treated groups were increased dose dependently. On the other hand, MFESF caused the GLLT-4 and leptin mRNA expressions in adipose tissue to decrease dose dependently, which means that triglyceride synthesis in adipocytes might be decreased and consequently signals adipocytes to inhibit the synthesis and release of leptin. Hepatic ACC mRNA expression in MFESF-treated groups was also decreased. and this may result in lowering of serum triiglyceride level. In contrast, liver GLUT-2 mRNA expressions in MFESF-treated and acarbose groups were increased. Higher rate of glucose uptake into hepatocytes is known to inhibit a phosphoenolpyruvate carboxykinase (PEPCK)-catalyzed reaction, which is a rate-limiting step in gluconeogenesis.