Androgenic alopecia (AGA) encompasses both male and female pattern hair loss and is a common form of hair loss in both men and women. Its onset usually occurs in the third or fourth decades of life in men, with later onset in women. AGA does rarely occur, however, in the pediatric population, called adolescent AGA. Adolescent AGA is pattern hair loss occurring in boys and girls younger than 18 years, whereas early-onset AGA refers to pattern hair loss before 35 years of age. A sixteen-year-old girl visited our department complaining of diffuse hair loss on the crown for 5 years. Her father had history of AGA. Hair pull test was negative. Laboratory tests including serum estrone, free testosterone level and thyroid function test were within normal limit. Phototrichogram analysis revealed diffuse thinning of hair on the midscalp and the percentages of thin hair and short hair were higher on the midscalp than the occiput. We diagnosed the case with adolescent AGA. A number of studies published in the last decade have helped to elucidate the prevalence of adolescent AGA, have clarified the genetic as well as physiologic mechanisms underlying hair loss, and have revealed the associated psychologic and systemic morbidities. Clinicians should consider AGA as a differential diagnosis for adolescent hair loss.