BACKGROUND: Hidradenitis suppurativa is a relatively rare chronic dermatosis with a severe and treatment-resistant course that significantly impairs patients’ quality of life and poses a serious medical and social issue. AIM: To evaluate the clinical and immunological efficacy of secukinumab in patients with hidradenitis suppurativa. METHODS: The study included 12 patients (7 men and 5 women) aged 12 to 52 years with hidradenitis suppurativa. A control group comprised 20 conditionally healthy volunteers. The severity and dynamics of clinical symptoms during treatment were assessed using the Hidradenitis Suppurativa Severity Index. T helper cells (Th) were analyzed using CD3 and CD4 antibodies. Th cell differentiation was assessed with CD45RA and CD62L markers. Serum interleukin levels were measured via enzyme immunoassay. All 12 patients with hidradenitis suppurativa received secukinumab for 16 weeks. RESULTS: Positive changes in the clinical course of hidradenitis suppurativa were observed within one week of initiating secukinumab gene-engineered therapy, with continued regression of efflorescences leading to significant clinical improvement by the end of the 16-week treatment course. Treatment resulted in normalization of peripheral blood levels of Th17 and Treg cells, as well as Th17/Treg and IL-17A/IL-10 ratios. CONCLUSION: A pronounced Th17/Treg imbalance may serve as a marker of disease severity in hidradenitis suppurativa and a rationale for initiating biologic therapy with secukinumab. © 2025 Elsevier B.V., All rights reserved.