The systemic changes induced by inflammation have been referred as the acute-phase response. The changes in the concentrations of acute-phase proteins are due largely to changes in their production by hepatocytes induced by pro-inflammatory cytokines. Because of its specificity, sensibility and short half-life, C-reactive protein is the most useful indicator among all the acute-phase proteins. The clinical strategy to deal with an acute-phase response is to search the aetiology: infections, neoplasms, auto-immune and allergic diseases. The treatment of an acute-phase response is the treatment of its aetiology.