Hair loss is a common problem in men and women. Correct diagnosis of hair disorders is complex and requires evaluation of clinical presentation, history, physical examination, and laboratory tests. Hair loss may be categorized as hair shaft abnormalities, permanent alopecia, or nonpermanent alopecia. Nonpermanent alopecia, the most common type, includes androgenetic alopecia, telogen effluvium, alopecia areata, and traction alopecia. The hallmark of this group is the possibility of complete regrowth with adequate treatment.