This article presents two cases of ectopic pregnancy in the ovary and rudimentary horn, which had a life-threatening course. Despite availability of modern high-quality diagnostics, determining the condition remains challenging, because the definitive diagnosis is established and confirmed only intraoperatively. Hence, the clinical picture can be used primarily in making a diagnosis and choosing an appropriate treatment strategy. Rare localizations, such as in the ovary and rudimentary horn, which cause difficulties in making a diagnosis, should not be overlooked. If an ectopic pregnancy is not detected promptly and the risks are underestimated, death may occur. Two clinical cases clearly demonstrate timely diagnosis, regardless of additional examination methods (e.g., pelvic ultrasound, human chorionic gonadotropin test), and adequate choice of access and scope of surgical intervention. Moreover, the lack of awareness among women about this type of pathology should be considered. Patients often do not complain, do not remember the date of their last menstruation, do not monitor their menstrual cycle, and do not seek medical help in a timely manner. The combination of several factors can lead to fatal events. In this study, both cases of ectopic pregnancy with a rare localization ended favorably.