Objective: To assess the relation between the preoperative serum level of C-reactive protein (CRP) and the WBC count and the efficacy of emergency cervical cerclage. Study Design: We retrospectively reviewed the medical records of 17 women (16 singleton pregnancies and 1 twin pregnancy) who underwent emergency cervical cerclage (McDonald technique) between 21 and 26 weeks of gestation. The uterine cervix was dilated ≥3.0 cm and the intact (not ruptured) fetal membranes were visible or protruded into the vagina in all patients. The serum level of CRP and the WBC count were determined preoperatively and postoperatively. Emergency cervical cerclage was considered successful if delivery occurred ≥14 days after the procedure. Results: Emergency cervical cerclage was successful in 12 women, including the woman with a twin pregnancy, but failed in 5 women. The preoperative serum level of CRP and the WBC count were significantly lower and dilatation of the cervix was significantly less in the success group than in the failure group. Cerclage was successful in all eight patients with cervical dilatation ≤4.0 cm, but in only 4 of 9 patients with cervical dilatation >4.0 cm (p < 0.05). Cerclage was successful in all 11 women with a preoperative serum level of CRP ≤4.0 mg/dl and a WBC count ≤14,000/µl compared with 1 of 6 women with either a CRP level >4.0 mg/dl or a WBC count >14,000/µl (p < 0.01). Conclusion: A preoperative CRP value ≤4.0 mg/dl, a WBC count ≤14,000/µl, and cervical dilatation ≤4.0 cm were significantly associated with prolongation of pregnancy after emergency cervical cerclage.