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Background: Alopecia areata (AA) is believed to have an autoimmune mechanism in which the hair follicles are targeted by CD4+ and CD8+ lymphocytes. Studies investigating the autoimmune mechanism of other cutaneous diseases, including vitiligo, showed that T reg is a component of cutaneous immune privilege. Our study uses immunohistochemical staining in formalin-fixed, paraffin-embedded tissue to examine the percentage of CD4 + FoxP3 + , CD25 + FoxP3 + , and CD8 + FoxP3 + T reg in AA in human specimens., Methods: Immunohistochemical double staining for CD4 + FoxP3 + , CD25 + FoxP3 + , and CD8 + FoxP3 + was performed on 12 AA cases and 12 other autoimmune and non-autoimmune cutaneous diseases. The frequency of CD4 + FoxP3 + , CD25 + FoxP3 + , and CD8 +  FoxP3 + T reg was counted and expressed as a percentage of total CD4 + , CD25 + , and CD8 + lymphocytes, respectively, in order to account for intersample inflammatory response variability., Results: There was a significant reduction in the mean frequency of CD4 +  FoxP3 + and CD25 +  FoxP3 + in AA when compared to other autoimmune and non-autoimmune cutaneous diseases., Conclusion: T reg is significantly lower in AA when compared to other cutaneous diseases. Additionally, this immunohistochemical-staining protocol may be useful to evaluate T reg in formalin-fixed, paraffin-embedded specimens for other cutaneous diseases. Studies examining T reg in AA and other cutaneous diseases may have implications for future interventions., (© 2019 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)