Necrotizing fasciitis is an infection which involves soft tissues up to the fascia, with wide areas of necrosis, and is mainly caused by group A beta-hemolytic Streptococcus. The Authors report a case recently observed and after an accurate review of the Literature, taking into account the most recent pathogenetic knowledges, confirm the necessity of an early diagnosis based on clinical criteria but above all on histological biopsy. The treatment is mainly surgical, and allows, together with the medical treatment, to subdue the rapid progression of the infection which notwithstanding maintains an high mortality rate.