Only a few cases of premenarcheal endometriosis have been reported in the literature, and bladder endometriosis accounts for 1% of all cases of endometriosis. The authors report the case of an 11-year-old girl who presented with macrohematuria due to bladder endometriosis without apparent menarchal discharge from vagina, and was initially diagnosed as premenarcheal endometriosis. MRI revealed that the lesion penetrated the bladder musculature and infiltrated the anterior wall of the lower uterine segment. She underwent transurethral biopsy and hemostasis, which revealed bladder endometriosis. After three months, she again presented with macrohematuria without exacerbation of bladder endometriosis. Periodic macrohematuria occurred after her basal body temperature dropped. Transrectal ultrasound revealed a fistula in the bladder and the internal cervical os. This is the first report of bladder endometriosis without menarchal discharge, which should be kept in mind when considering differential diagnosis of adolescent macrohematuria without apparent menarche.