Aims: We present this case to improve medical knowledge about unusual presentation of leiomyomas and about the diagnostical findings of examinations settled down per rectal way. We provide images and stress the importance of differential diagnosis based on imaging. Presentation of the Case: We report a case of a 26 years old nulliparous, with a leiomyoma developed on the posterior upper third of the vagina surgically removed. The patient came to our Unit with dysmenorrhea and menorrhagia and underwent physical examination and ultrasound scan. Both exams were executed per transrectal way because of her being a virgo. A Computed Tomography scan has been executed too. All the results pointed out the presence of a round-shaped, well delimitated, solid mass in posterior vaginal wall. Magnetic Resonance confirmed this diagnosis. Discussion: We widely discuss the symptomathologic cortege, the diagnostic iter based on imaging we settled down, the possible differential diagnosis, and surgical therapy performed. Concordance of imaging, negativity of tumor markers and general well-being status of the patient led to the diagnostical hypotesis of vaginal benign neoformation. These data excluded other diagnosis as endometriosis, uterine fibroma, primitive vaginal malignant tumor and metastasis of other-site primitive malignant neoplasia. The patient has been treated by surgical transvaginal excission therapy. Conclusion: US imaging and MR gives us the possibility to recognize a mass and to discern his nature and localization, thus to choose the best therapy in each case. Hystopathology still represent the gold standard in making a diagnosis in gynaecological oncology.