The longitudinal line in the middle of a woman’s lower abdomen is the mid-abdominal line, which is an important marker of female physiology. There is a small amount of pigmentation under the skin of the midsection, which makes it appear as a light gray longitudinal line. In some women, due to the elevation of androgens in the body, the pigmentation in the midline can be deeper than in other women, and therefore the midline is more visible than in other women. The presence of the midline is a normal female physiological manifestation and does not require special treatment. However, if the midline is obvious and the body hair is heavy, the patient should go to the hospital as soon as possible to have a sex hormone test to assess the level of androgens in the body. If the androgen level is too high, medication should be applied as soon as possible to restore the normal female endocrine level.