The thickness of a woman’s endometrium is not constant and varies with hormone levels at different times of the menstrual cycle, as well as with the age and ovarian function of the woman. If the patient is a woman of childbearing age with normal ovarian function, the thickness of the endometrium is 11 mm, which is normal if it is just before the onset of menstruation. If it is just after menstruation or during ovulation, an endometrial thickness of 11mm is not normal and excessive thickness suggests the possibility of endometrial lesions. If the thickening is still present, hysteroscopy should be done to determine if there is cancer of the endometrium or if it is caused by some lesions such as polyps or submucosal fibroids. If the patient is post-menopausal, endometrial thickness of 11mm is not normal. The thickness of endometrium should be less than 0.5cm after menopause in women, and hysteroscopy is needed.