DEAR EDITOR, Hidradenitis suppurativa (HS) is a relapsing inflammatory skin disease. The cytokines interleukin (IL)-1b, IL-12, IL-23, IL-17 and tumour necrosis factor (TNF)-a are involved in the inflammatory process. 1 The only approved drug for the treatment of moderate-to-severe cases is adalimumab (a TNF-a inhibitor). However, long-term clinical responses range only from 52 to 57%. 2 Tildrakizumab (anti-IL-23), 3 guselkumab (anti-IL-23) 4 and ustekinumab (anti-IL-12/23) 5 have been successfully used in HS.Risankizumab is a humanized IgG1 monoclonal antibody selective to IL-23. It is currently approved for the treatment of moderate-to-severe plaque psoriasis in adults. 6 We describe two patients with severe Hurley Stage III HS, successfully treated with risankizumab:Patient 1 was a 39-year-old woman, a nonsmoker with a body mass index (BMI, kg m -2 ) of 28Á9. Her medical history included depression and multiple sclerosis (MS). Her mother and grandfather have been treated for HS. Historically, she was treated with systemic azithromycin, doxycycline, clindamycin, rifampicin, isotretinoin and, lastly, adalimumab (40 mg per week subcutaneously). Three months after starting adalimumab, she achieved a Hidradenitis Suppurativa Clinical Response (HiSCR). Loss of response (LoR) was observed after 20 months and consequently adalimumab was discontinued