Skin and soft tissue infections represent a heterogeneous group of clinical entities that require to be accurately identified for an appropriate and immediate management. Clinicians are challenged by the need to rapidly select those patients requiring hospitalization and medical therapy only and those to be immediately submitted to surgery. Erysipelas and several forms of cellulitis, involving the superficial structures of epidermis and dermis, are medical conditions; some cutaneous abscess may require surgical drainage, and all the necrotizing infections, involving the subcutaneous tissue (necrotizing fasciitis) or muscles (myonecrosis) are surgical conditions. Among the clinical clues useful for the diagnosis are the presence of severe pain disproportionate to the clinical evidence of the lesion (necrotizing fasciitis), the presence of crepitus (gas gangrene) and signs of systemic toxicity (high fever, hypotension, tachycardia, shock and multiple organ failure).