The term necrotizing soft-tissue infection (NSTI) encompasses a heterogenous group of patients with necrotizing infections, involving any body part. NSTI is diagnosed by surgical exploration, where necrosis of the subcutaneous tissue and/or muscle tissue, undermining of the skin, thrombosis of the superficial veins, and deliquescent tissue can be seen. Patients can present with vague symptoms, and approximately half of patients experience severe pain. The clinical presentation and microbiological etiology vary according to affected body site, with NSTI located to the extremities being dominated by monomicrobial group A streptococcal infections, and NSTI located to the anogenital area dominated by polymicrobial infections. No set of diagnostic criteria exists, and suspicion of the diagnosis should come from careful clinical examination and signs of local or systemic severity. Laboratory blood values show no distinct pattern but resemble those of sepsis. Imaging can aid the diagnostic process but must not delay surgical intervention.