Hidradenitis suppurativa is a skin disease involving the apocrine sweat glands which often becomes chronic. The aetiology is not completely known, but the mainstays of medical treatment are antibiotics, which gives temporary relief but do not essentially alter the course of the disease. We describe our results of treating 138 affected patients by radical excision of the diseased areas between 1978 and 1999. Postoperative follow-up ranges from 3 months to 21 years; we compiled data from the patients' casenotes and circulated a questionnaire, which 116 patients completed. Median age at onset of disease was 23 years and the interval before radical surgery was 10 years. Altogether 367 affected sites were excised; most cases required skin grafting. There were no serious surgical complications. In 38 patients (33%) the disease recurred to some degree, and 14 of them required further operation. Six patients had a subsequent operation to improve the aesthetic result. Ninety-six of the patients (83%) answered that they would recommend the procedure to other patients under similar circumstances. In our opinion excision and skin grafting is a valuable treatment in cases of severe hidradenitis suppurativa.