Recurrent herpes labialis (RHL) is a common skin disease that is often caused by herpes simplex virus type I (HSV-1), but its immunology and pathogenesis remain unclear. The balance of Th17/Treg cells is crucial for maintaining immune homeostasis. This study aimed to investigate whether the balance of Th17/Treg cells and related cytokines may be a determinant occurrence in patients with RHL. This is a clinical experimental research based on clinical observation and analysis. We collected RHL patients from the outpatient clinic of the Department of Dermatology of Zhejiang Chinese Medical University (Hangzhou, China) in 2017, conducted questionnaire survey and signed informed consent. Peripheral blood was collected from 30 patients with RHL and 30 healthy volunteers. Flow cytometry was used to detect the percentages of Treg cells and Th17 cells. Protein microarrays coated with 20 cytokines related to T-cell subsets were performed. Enzyme-linked immunosorbent assay (ELISA) assay was conducted to further verify the expression levels of the cytokines that were screened by protein microarrays. Percentages of Th17/Treg cells in peripheral blood of RHL patients were significantly increased compared to those in healthy volunteers. The fold changes of GM-CSF, IL-4, TGF-β, IL-12, IL-10, IL-17F, and TNF-α were significantly increased compared with healthy volunteers. In addition, the expression of IL-4, IL-10, and TGF-β in the serum of RHL patients increased significantly. Our results indicated an imbalance of Th17/Treg cells in RHL, and this imbalance is probably an important factor in the occurrence, development, and recovery of RHL.Keywords: Th17/Treg; cytokine; herpes simplex virus; recurrent herpes labialis.