Necrotizing fasciitis is a severe, potentially fatal, soft tissue infection. Group A streptococci are the main infectious agents. Early surgical treatment is decisive for the outcome. This report includes 20 patients treated consecutively during a four and a half year period, ten women and ten men, 28 to 78 years of age. Condition at admission to hospital, time from symptom appearance to operation, treatment and results are described. All patients had signs of local infection with rubor and swellings. Severe localized pain was typical. Surgical diagnostic exploration confirmed the diagnosis and led to prompt surgical debridement of all affected tissues. Three patients died, 12 survived without severe sequela and five survived with amputated leg or arm. Necrotizing fasciitis has changed from being a rare disease primarily affecting immunocompromised patients to occurring more frequently also among otherwise healthy individuals. By diseases with local soft tissue infection a liberal use of surgical exploration leads to diagnosis. Increased knowledge of the disease and adherence to a treatment protocol based on antibiotic therapy and mandatory aggressive surgery has probably improved the results with no case fatality in the latter half of the study period.