Necrotizing soft tissue infections (NSTIs) are rare but potentially life-threatening infections involving the skin and underlying tissues such as fat, fascia, and sometimes muscle. They can progress rapidly and, despite modern antibiotics, surgery, and intensive care, are still associated with high in-hospital mortality. A major challenge in the management of NSTIs is early diagnosis. Initial signs and symptoms are often nonspecific and may resemble less severe soft tissue infections, leading to diagnostic and therapeutic delays. Once identified, treatment requires urgent surgery, broad-spectrum antibiotics, and close monitoring, frequently in an intensive care setting. Even with appropriate treatment, the clinical course of NSTIs is highly variable. Some patients recover, while others develop severe complications such as septic shock or multiple organ failure and may die during hospitalization. Predicting outcomes early in the hospital stay remains difficult for clinicians. The aim of this observational study is to identify factors associated with in-hospital mortality in adult patients with NSTIs. In-hospital mortality, defined as death from any cause during the hospital stay for NSTI treatment, represents the most severe outcome and is of major relevance to patients and caregivers. The study focuses on clinical and laboratory data routinely available at hospital admission or during initial emergency department evaluation. These include patient demographics, vital signs, and standard blood test results commonly obtained in early clinical assessment. No additional diagnostic tests or procedures are required for study purposes. Identifying early predictors of mortality is particularly important in NSTIs, given the rapid progression of the disease. Early recognition of high-risk patients may allow closer monitoring and more timely interventions. The study will be conducted in high-volume referral centers with extensive experience in NSTIs management, where care is delivered according to established international guidelines. All patients will receive standard treatment based on clinical judgment. No experimental therapies or changes in routine care will be involved.