Objectives To study the difference of serum leptin levels between alcohol dependent patients and the control group， and the relationship between serum leptin levels and the cognitive functions of alcohol dependent patients. Methods A total of 45 Han male patients from Northern China with the diagnosis of alcohol dependence based on the Diagnostic and Statistical Manual of Mental Disorders（ DSM- Ⅳ） were randomly selected. A total of 45 male healthy individuals were selected as the control group. Blood samples were collected from both groups， and the serum leptin levels were measured using enzyme-linked immunosorbent test. The cognitive functions were evaluated by Wisconsin Card Sorting Test（ WCST）. Results The level of serum leptin in the experimental group was higher than that in the control group， and the difference has statistical significance（ P＜0.001）. In the experimental group， the level of serum leptin was positively related to the total errors（ r=0.339，P=0.023） and the continuous errors（ r=0.372，P=0.012） of WCST while negatively related to the total corrects（ r=-0.339，P=0.023） and continuous corrects（ r=-0.327，P=0.029）. Conclusions The level of serum leptin in alcohol dependent patients is significantly higher than general population， and the higher the level of serum leptin is， the more severe the cognitive impairment becomes.