Candidate genes with a possible involvement in placental abruption are mainly those related to thrombophilia and preeclampsia. Some reports have shown by placental histologic investigation that increased risk of placental abruption is associated with prolonged inflammation. The polymorphic allele A2 in the gene coding for interleukin 1 receptor antagonist (IL1Ra) has been associated in various diseases of autoimmune or inflammatory nature. In obstetrics, previous research data has linked altered IL1Ra protein production with placental pathology and some severe pregnancy complications. In this study, we have determined whether IL1Ra gene polymorphism is associated also with an increased risk of placental abruption. The study involved 116 women with placental abruption and 112 healthy control pregnant women who were genotyped for polymorphism of the IL1Ra gene. The genotype and allele frequencies were assessed between the two groups and also compared with those in the general population. The frequency of the A2 allele was 28.0% among cases and 33.0% in controls (p=0.29), both similar to that in the general population (28.9%). In addition, the genotype distribution of IL1Ra polymorphisms was similar in both groups. Interestingly, there were a relatively higher number of cases with allele A3 (n=4; 1.7%) compared with the controls (0.4%) and the general population (1.0%) but the difference was not statistically significant. We conclude that there is no significant difference in IL1Ra polymorphisms between patients with and without placental abruption.