Natural CD4+CD25+FoxP3+ regulatory T cells (Treg) actively suppress physiological and pathological responses, therefore playing a critical role in controlling peripheral tolerance to self antigens and maintaining immune homeostasis. In normal individuals, natural Treg and interleukin- 10-secreting Treg are able to suppress Th2 responses to allergens, whereas lower levels of Treg or defect in their functionality have been described as potential mechanisms for inducing allergic diseases. In animal models, adoptive transfer of CD4+CD25+Treg has been shown as a promising strategy for preventing or treating allergic disorders. Recent studies show that induction of Treg activity is associated with suppression of allergic responses in allergic patients treated with specific immunotherapy. Herein, I review the potential of Treg as exciting targets for developing new immunotherapeutic strategies for treating allergic diseases.