Alopecia areata (AA) is an autoimmune disease with a genetic basis and environmental triggers. It presents as nonscarring hair loss ranging from few circular bald areas (patchy alopecia areata) to complete baldness of the head (alopecia totalis) or the entire body (alopecia universalis). Almost 2% of the population is affected once in a lifetime. The peak onset in childhood is before the age of 10. The genetic trait is complex and still not completely understood. Indeed, genome-wide association studies have given more insight into the pathogenesis of AA and opened new therapeutic options. It is now widely accepted that a collapse of the immune privilege of the hair follicle is responsible for AA activation which enables immune cells to attack the hair follicle. First studies using inhibitors of the JAK kinase pathway have shown promising results in the treatment of AA.