During November, 1992, to May, 1994, 13 patients were treated at Haukeland University Hospital, Norway, for necrotising fasciitis due to group A beta-haemolytic streptococci. 3 patients died, 1 before admission. Mucoid group A streptococci were isolated from affected tissue (12 patients) and/or blood (5). Strains from 11 patients were serotype M-1 (5 patients), M-3 (2), M-6 (2), M-28 (1), and M-untypable (T-1, opacity factor negative) (1). For the 12 patients admitted alive, the following preoperative events were recorded: 8 had clinical signs of shock with systolic blood pressure of 90 mm Hg or less, 8 had impaired renal function, and 7 had biochemical markers of disseminated intravascular coagulation. At least 6 patients fulfilled the criteria for streptococcal toxic shock syndrome. Preoperative C-reactive protein was substantially raised ( > 200 mg/L) in 10 patients. The 12 patients were given high doses of antibiotics and were operated on with aggressive debridement of necrotic skin and fascia, 7 of them within 24 h of admission. The increasing incidence of necrotising fasciitis in western Norway reflects the resurgence of invasive group A streptococcal infections documented in Scandinavia since 1987. The high case-fatality rate can be reduced by early diagnosis and aggressive surgery combined with adequate antibiotic therapy.