Eyebrows are a critical facial feature that helps to define the way we look. In any ways, eyebrows are more important to one’s appearance than scalp hair, as eyebrows are in a more central position on the face and serve to frame the eyes (the single most important facial element). Unlike the loss of scalp hair, the loss of one’s eyebrows is not viewed as a natural process and is, therefore, not cosmetically acceptable. Eyebrows may be lost for a variety of reasons including thyroid and other systemic diseases, alopecia areata, burns, tattoos, infections, repeated plucking, congenital inability to grow eyebrows and a genetic tendency for eyebrows to thin, or disappear, over time. Eyebrow restoration is similar to other hair transplant procedures performed on the scalp, in that, for appropriate candidates, the transplanted hair is permanent. However, because eyebrows have their own unique attributes, eyebrow transplants differ from hair transplants in a number of important ways. Eyebrow Anatomy and Physiology The direction of eyebrow hair changes dramatically in different parts of the brow. In the region of the eyebrow nearest the nose, the hair points upward. The hair across the top of the eyebrow points outward and downward. The hair in the lower part of the brow grows outward and upward. This criss-cross growth pattern causes the hairs in the middle of the eyebrows to converge and form a subtle natural elevation running horizontally through the middle of each eyebrow. The second distinctive characteristic of eyebrow hair is that the hairs emerge from the follicle at a very acute angle so that the hair grows flat to the skin’s surface. This is in contrast to scalp hair where the angle between the hair and scalp can be 45 degrees. The third important feature of the eyebrows is that the hairs grow as individual strands, rather than in the 1- to 4-hair follicular unit grouping that are characteristic of scalp hair. The fourth distinctive element of eyebrow hair is that the hair growth cycle is very short. This means that eyebrow hair will grow (in anagen) only for about 4 months before it enters the resting (telogen) phase and falls out. In contrast, scalp hair has a growth phase that can last 3 to 7 years, enabling the scalp hair to grow much longer.