The aim of the study was to evaluate the effectiveness of the treatment of patients with a diagnosis of ectopic pregnancy treated conservatively with Methotrexate (MTX), assessment of fertility and pregnancy rates after therapy and search for early biochemical markers of ectopic pregnancies and pregnancies of unknown localization (PUL).The study included 126 patients. 97 patients were qualified for MTX treatment. Among 21 pregnant patients, who were firstly considered as PUL, and later on diagnosed as ectopic, serum proteins HSP-10, HSP-27 and PSG-11 were measured. 88 patients (90,72%) of treated with MTX were effectively cured without the need of surgery. Among 34 patients on follow-up, 8 (23.5%) did not attempt to conceive again, whereas 26 patients declared their wish to conceive again. The attempt proved to be successful in case of 16 women (61.53%), and they gave birth to healthy children. Serum concentration levels of HSP-10, HSP-27, and PSG-11 were significantly higher in pregnancies at risk of spontaneous abortion as compared to ectopic pregnancies. Systemic conservative treatment of ectopic pregnancy with MTX is effective and safe. It allows to cure the majority of patients, especially in „double dose” regiment. High delivery rate of healthy children, is a positive asset of MTX treatment. The results of the study indicate high value of PSG-11, HSP-27 and HSP-10 serum concentrations as predictors of correct implantation site.