Background: The occurrence of ovarian hematoma during controlled ovarian stimulation (COS) is very rare. Until now, there is no such case reported in the literature. In this study, an attempt was made to discuss the possible mechanisms for the development of hematoma in such patients, the clinical presentation, monitoring, and management of these cases. Case Presentation: A rare case of periovarian hematoma was reported in a patient with a history of endometriosis undergoing ovarian stimulation for in vitro fertilization. On the seventh day of stimulation, the patient complained of severe pain in the abdomen. Her vitals and blood investigations were within normal limits. On abdominal examination, mild tenderness was noted in the left iliac fossa. On vaginal examination, fullness and tenderness were noted in the left fornix. On ultrasound, probe tenderness was present and a left ovarian hematoma measuring 2.0x1.81x1.55 cm was observed. She was managed conservatively. The hematoma exhibited a gradual reduction following the pick-up procedure and eventually resolved completely within a month. Conclusion: Underlying endometriosis could be one of the possible causes of this periovarian hematoma. A conservative approach with close monitoring forms the first-line management in hemodynamically stable patients.