Abstract: Objective To explore the relationship between serum IL-18 and Postpartum depression.Methods A total of 78 women with postpartum depression (PPD group, n=78) and a total of 62 women without postpartum depression (NCI group, n=62), who delivered at the First People's Hospital, were enrolled in this study. They were evaluated by the Edinburgh Postnatal Depression Scale (EPDS). The concentration of serum IL-8 in the two groups was determined by enzyme-linked immunosorbent assay (ELISA).Results The serum levels of IL-18 in PPD and NCI groups were (31.95 ±7.42) ng/ml and (22.51 ±5.04) ng/ml respectively.There was statistically significant difference between the two groups (P<0.05). The EPDS scores in PPD and NCI groups were (20.06 ±3.50) and (12.53 ±3.65), respectively, which was statistically significant (P<0.05). The Pearson correlation analysis of EPDS score and serum IL-18 concentration in group PPD showed positive correlation (P<0.05).Conclusion The concentration of serum IL-18 may be used as a biochemical indicator of postpartum depression.