Objective. A wide range of lesions, including a mesothelial cyst of the uterine round ligament, are included in the differential diagnosis of a groin mass. Our study emphasizes the rarity of this ailment and the significance of correct preoperative diagnosis in guiding our treatment approach. Case Report. A 43-year-old female patient, presented to our hospital with a five-year his- tory of swelling and slight discomfort in the right groin. A nonreducible inguinal mass with greater projection during a Val- salva maneuver was found. An abdominal CT scan revealed a well-defined lesion located near the right horn of the uterus and extending through the inguinal canal. The patient was brought to the operating room with the clinical suspicion of an inguinal hernia. A soft mass measuring 4.5×2×1.8cm was discovered in the right round ligament, and it was surgically removed. Histo- pathological examination confirmed a mesothelial cystic lesion. The patient’s condition, after a period of 12 months, continues to be satisfactory. Conclusion. Few cases of uterine round ligament mesothelial cysts have been reported worldwide. Their cause is unknown, and preoperative diagnosis is unreliable. Resection relieves symptoms, and histological examination of the surgical specimen confirms the diagnosis. Additional clinical cases are needed to create a systematic clinical approach.