Objective: To investigate the clinical results and prognostic factors of multiple dose methotrexate (Mtx) treatment of ectopic pregnancy patients with high initial serum (human chorionic gonadotropin [hCG]). Design: Retrospective cohort study. Patients: Twenty-six ectopic pregnancy patients with serum (βhCG) > 5,000 mIU/mL who received multiple doses of Mtx (1 mg/kg) with folinic acid rescue on the alternating days. Results: Success rate was 88.5%. All failures were tubal ruptures in those who underwent surgery. Median initial hCG values of the success and the failure patients were 8,582 (5,058–31,114) and 5,280 (5,042–13,563) mIU/mL respectively (p > 0.05). Side effects were seen in 18 patients (69.2%, one bone marrow suppression and 17 minor side effects). The number of Mtx injections (7.04 ± 1.71), Mtx dose (71.35 ± 13.16 mg) and follow-up period (42.04 ± 23.77 days) did not differ between groups. Body mass index (BMI), Mtx dose, number of Mtx and change in βhCG levels between the initials and the levels measured 2 days after the 3rd, 4th, and 5th Mtx injections were found to be highly predictive for tubal rupture. Conclusions: Multiple-dose Mtx treatment of ectopic pregnancies with high initial hCG is safe and effective. BMI, Mtx dose, number of Mtx injections and the decrement of βhCG levels were found as highly predictive for the success of the treatment.