An endometrial lining of 2 centimeters is not normal and may be associated with endometrial disease, which is more serious and requires treatment. The thickness of the lining of the uterus is in a constant state of flux and is usually within the normal range as long as it is less than 1 centimeter. The lining of the uterus will thicken as it progresses through the secretory and proliferative phases, but usually not more than 1 centimeter. If the thickness of the endometrium exceeds 1 cm, e.g. 2 cm, it is rare for the endometrium to exceed 2 cm in non-pregnancy periods, so this condition is considered to be an endometrial-related disease and requires medical consultation and treatment. If atypical hyperplasia is present, it is precancerous and is serious and intervention is necessary.