Background: Atopic dermatitis (AD) is one of the most common inflammatory skin diseases, with an increasing incidence in clinical practice. AD models have demonstrated that TGF-β signaling is compromised in regulatory T cells (Tregs). Objectives: This study aimed to investigate the TGFβ-dependent in vitro conversion of CD4 + CD25 -T cells derived from AD-patients into CD4 + CD25 + Foxp3 + induced Tregs (iTregs) in comparison to healthy controls. Methods: To analyze in vitro iTreg conversion, human CD4 + CD25 -T cells were cultured on anti-CD3-coated plates in the presence of TGF-β and IL-2 for up to 3 days. Consequently, the underlying mechanism of impaired CD4 + CD25 + Foxp3 + iTreg generation was explored by focusing on TGF-β signaling. Finally, the functionality of iTregs was investigated. Results: Conversion of CD4 + CD25 -Foxp3into CD4 + CD25 + Foxp3 + iTregs was diminished in AD individuals. Impaired iTreg generation was accompanied by a reduced surface expression of GARP (glycoprotein A repetitions predominant), a marker for activated Tregs. A reduced expression of Smad3 mRNA was revealed in CD4 + CD25 -T cells. Interestingly, the sup-pressive quality of iTregs was found to be equal in cells derived from AD and healthy donors. Conclusion: The signaling effect of TGF-β receptors on the suppressor quality of iTreg conversion is conserved. Impaired iTreg generation might be a reason for the lack of immune suppression in AD patients and contributes to the chronicity of the disease.