We report a case of right ovarian dermoid cyst fistulized in the bladder and revealed by recurrence urinary infections. The diagnostic has not been conformed but 5 years after the urinary first manifestations. The cystoscopy has been a cardinal importance but the right seat of the lesion has been determined only during laparotomy. This unusual complication of ovarian dermoid cyst must call the practitioner's attention to urinary symptoms with a pelvic tumour. Moreover, the left ovary agenesis and the young patient's age have constrained the surgeon to preservative method. The functional efficiency of this method has been proved by the periods recovery, 5 months later.