Abstract: The aim of this study was to evaluate the effects and mechanisms of berberine (BBR) against dexamethasone (Dex)-induced metabolic disorders. 3T3-L1 cells were differentiated by Dex treatment and then treated with BBR (2.5, 5, 10 μmol·L^-1). Lipid accumulation was detected using oil-red O staining. After review and approval of the ethics committee of the Institute of Materia Medica, Peking Union Medical College, Chinese Academy of Medical Sciences, C57BL/6N mice were randomly divided into three groups. In the BBR treatment group, mice were subcutaneously implanted with an osmotic pump containing Dex and gavaged with BBR (100 mg·kg^-1·day^-1) for 4 weeks. The model control group was implanted with a Dex osmotic pump with no other treatment. Mice given a saline-filled osmotic pump were used as a negative control. During the study, food intake and body weight were measured weekly. Subcutaneous fat and visceral fat was detected by MRI. At the end of the experiment the plasma levels of total cholesterol (CHO), triglyceride (TG), low-density lipoprotein cholesterol (LDL-c), high-density lipoprotein cholesterol (HDL-c), glucose (Glu), and muscle mass were measured. The expression of peroxisome proliferator-activated receptor γ (PPARγ) and AMP-activated protein kinase α (AMPKα) in 3T3-L1 cells and epididymal fat of C57BL/6N mice was evaluated through RT-PCR and Western blot analysis. The results showed that BBR inhibited Dex-induced adipocyte differentiation in 3T3-L1 preadipocytes by up to 23% in a dose-dependent manner. In C57BL/6N mice, berberine alleviated hyperlipidemia and hyperglycemia and reduced visceral fat accumulation induced by Dex. The results from RT-PCR and Western blot analysis showed that BBR reduced PPARγ expression and increased the phosphorylation of AMPKα in 3T3-L1 cells as well as in adipose tissue. Berberine might alleviate Dex-induced metabolic disorder and visceral fat accumulation by modulating PPARγ and AMPK expression.