Skin and soft tissue infections (SSTIs) are non-complicated infectious processes, such as cellulitis, abscesses or infected wounds. Among them, the complicated ones can be defined necrotizing soft tissue infections (NSTIs), described in several classification systems based on their anatomic location, causative pathogen(s), rate of progression, depth of infection, and severity of clinical presentation. Among the NSTIs it is possible to identify necrotizing cellulitis, necrotizing myositis and necrotizing fasciitis. Patients with NSTIs may be critical: up to one-half of them develop septic shock and/or require mechanical ventilation and a third of them develop acute kidney injury. The mortality rate reaches 30% worldwide. NSTIs are typically caused by several different types of bacteria such as Streptococcus pyogenes (group A Streptococcus), Staphylococcus aureus, Clostridia and Vibrio species. These infections often start with symptoms similar to other skin infections but differently from them there is a rapid deterioration of the patient’s clinical condition. A prompt diagnosis is crucial considering that a delay in diagnosis and consequently in treatment ends in an increase of mortality. Treatment is based on: prompt surgical source control, adequate antibiotic therapy, supportive measures with intensive care if needed, with a daily multidisciplinary reassessment of the patient’s condition and a multidisciplinary management.