Introduction Alopecia areata (AA) is a T cell-dependent, organ-specific autoimmune disease. Topical diphencyprone is the treatment of choice in extensive AA. Materials and methods This study describes a series of 104 patients with extensive AA treated with topical diphencyprone to assess the efficacy and adverse effects of this drug. Results After a mean follow-up of 1 year, most patients in our series (87.5%) showed some response to treatment. Among responders, approximately half the patients had a poor response (grade 1-2) and the other half a higher response (grade 3-4). Adverse effects were mostly local and mild and included blistering, exudation, postinflammatory hyperpigmentation and microadenopathies. Conclusion We conclude that immunotherapy with diphencyprone is easy to implement, effective and well tolerated by patients. © 2013 Elsevier España, S.L. All rights reserved.