Objectives: To evaluate if, when considering expectant management in tubal ectopic pregnancy if the complementary use of Methotrexate could provide better results. We evaluate the success of treatment and the time required for titers of β-hCG to become negative. Methods: A double-blind randomized study, held at the Department of Obstetrics UNIFESP. The patients will be divided into two groups: in one patients will be administered a single intramuscular dose of 50 mg/m2 of Methotrexate and in the other patients will be prescribed Placebo intramuscularly. The monitoring will be done by measurement of β-hCG in the 4th and 7th day. When the decline of beta-hCG titers was > 15% in this interval, the patient was followed with weekly dosing of β-hCG until the titers become negative. The criterion of success is when the β-hCG was negative. The treatment failure occurs when surgery was necessary.