Summary Background  Hidradenitis suppurativa is a chronic inflammatory skin disease characterized by abscess formation, predominantly in the axillae and groins. The disease is difficult to treat and has a severe impact on quality of life. Recently, several case reports have been published describing successful treatment of hidradenitis suppurativa with infliximab and other tumour necrosis factor α inhibitors. Objectives  To evaluate the long‐term efficacy of a single course of infliximab. Methods  Ten patients with severe, recalcitrant hidradenitis were treated with infliximab (three infusions of 5 mg kg−1 at weeks 0, 2 and 6) and followed up for at least 1 year. The disease activity was measured using laboratory parameters and a recently developed acne score. The patients rated the efficacy of infliximab on a 10‐point scale at regular intervals. Quality of life was measured before and after treatment using the Dermatology Quality of Life Index (DQLI). Results  All patients improved within 2–6 weeks. The average acne score diminished from 164 ± 50 (mean ± SD) before treatment to 89 ± 49 after 1 year (P = 0·002). The mean CRP (C‐reactive protein) was reduced from 31·7 mg mL−1 to 5·5 mg mL−1 after 1 month (P = 0·015). Patients judged the efficacy with a score of 7·9. The mean DQLI was reduced from 18·4 ± 7·9 before treatment to 9·3 ± 9·1 after 1 year (P = 0·007). In three patients long‐lasting improvement was observed, with no recurrence of lesions in a 2‐year follow‐up period. The other patients showed recurrence of lesions after 8·5 months (range 4·3–13·4 months). Conclusions  Infliximab is an effective treatment in severe hidradenitis suppurativa, leading to reduction of symptoms for a prolonged period.