Alopecia areata is a frequent cause of hair loss. The origin of disease is not fully understood. However there are indications for a T-cell mediated autoimmune process. Genetic, immunologic and psychologic factors are important for the outbreak of disease. Most patients show localized patches of acute hair loss, where regrowth is observed spontaneously or with simple topical treatment within few months. In up to 15% of patients severe forms of disease can develop with total scalp (alopecia totalis) or scalp and body hair loss (alopecia universalis). There are only few known risk factors for development of a severe form. Although spontaneous remission is possible in these cases, it occurs rarely and treatment is difficult. Multifocal alopecia areata responds to intravenous high-dose corticosteroids. Topical immunotherapy with diphenylcyclopropenone (DPC) or PUVA therapy may be effective in longstanding and widespread disease. The unpredictable course of disease is a major handicap for clinical trials and treatment recommendations. Contact of patients with self-help organisations may be of help for coping with the disease.