Hair abnormalities can have tremendous psychosocial impacts on adolescents and young adults, and may cause a great amount of anxiety regarding physical appearance, associated illnesses, and potential clinical course. The pathophysiology of such disorders may vary,with potential congenital, infectious, autoimmune, nutritional, or environmental causes. Hair abnormalities may present as changes in hair appearance or quality, becoming weathered or fractured.An abnormal increase in hair is present in hypertrichosis and hirsutism, whereas a thinning or shedding of hair is evident in patients with telogen effluviumand alopecia areata. Diagnosis is focused on a detailed clinical history and physical exam, in addition to laboratory testing, a variety of clinical diagnostic tests, and scalp biopsy, which may be necessary to confirm some diagnoses. Many hair disorders have no cure, but clinicians can have a positive impact on their patients by identifying the abnormality and educating the patient regarding disease course. However, some conditions such as infectious hair disorders or scarring alopecia should be identified promptly to initiate treatment and ensure clinical improvement or optimal outcome.