Background: Ectopic pregnancies are a life-threatening emergency since they can invade maternal blood vessels, causing catastrophic hemorrhage and it is the leading cause of maternal mortality in the first trimester, and it accounts for 3 % of all pregnancy-related deaths even in developed countries. Objectives: To investigate the predictive factors for the requirement of additional doses of methotrexate in women with ectopic pregnancy treated with a single dose methotrexate regimen. Study design & settings: A prospective study was conducted on the gynecological and obstetrics department in Salah Aldin teaching hospital for the one-year duration from the 1st of Feb. 2020 to the end of Nov. 2020. Whereas 125 patients were included in this study divided into two groups [one group A (75) was treated with a single dose of methotrexate and group B (50) with multiple doses]. Results: The mean age group was between 20-29 years; the patient with a success treatment rate with a single dose was 73.3%, while for those who were treated with multiple doses with 64% success rate. Highly significant reduction in serum ß-hCG for ectopic pregnant women treated with a single methotrexate dose after four days and seven days of treatment. The resolution time was 31±SD days for those who were treated with a single dose, while it was 56±SD days for the multiple doses. Conclusion: The single dose of the methotrexate therapy could be positively offered to most stable patients experiencing medical management of an ectopic pregnancy, and a decline in the serum level of β-hCG between days 1 and 4 is related with a high treatment success rate. The change in the serum level of β-hCG between days 1 and 4 appears to be an early predictive factor of an additional dose of methotrexate.