\[Abstract\]ObjectiveTo investigate the association of serum leptin level with erectile dysfunction (ED). MethodsA total of 38 out-patients complaining ED were graded by using IIEF-5 questionnaire. The mean IIEF-5 score of the patients was (12.3±2.4)and no one was higher than 21. The patients were divided into 3 groups according to their scores. The fasting serum leptin levels were determined by ELISA in 38 patients (patient group) and 15 healthy controls (control group). Their body weights and heights were measured for body mass index(BMI). ResultsSerum leptin levels were significantly correlated with BMI in both groups, regardless of patient ages and history. The mean leptin level in patients was (10.16±8.67) μg/L, which was significantly higher than that in the healthy controls (\[4.81±3.66\] μg/L,P<0.05) after adjusting the effect of BMI. The leptin levels in the mild, moderate, and severe ED groups were (6.98±4.99) μg/L, (10.3±9.51) μg/L and (13.1±10.02) μg/L, respectively, with that of the mild group being significantly lower than those of the latter two groups(P<0.05). Conclusion It is indicated that human serum leptin level may have a potential value in diagnosing ED.