Prepubertal vaginal bleeding is considered as isolated menarche when, in the absence of detectable abnormality, it is not accompanied by any evidence of sexual development. The etiology remains unclear and various hypotheses have been put forward. This is the first time that a series of ultrasound patients with prepubertal menarche whose investigation has included imaging with ultrasound has been described. This paper illustrates isolated prepubertal menarche without the presence of an endometrial echo.