In-hospital emergency is a system designed to ensure an adequate response, in rapidity and appropriateness, to cardiac arrests and other medical emergencies, in general wards and in not-medical areas of the hospital. Early treatment of unstable patients, hospitalized in non-intensive care unit, reduces the incidence of serious adverse events such as unexpected cardiac arrest, unplanned intensive care admissions, and unexpected death.The Rapid Response System (RRS) describes the entire process of in-hospital emergency planning. The afferent limb of the RRS is the way, managed by the ward staff, doctors and nurses, to identify the patient in crisis, at risk of physiological deterioration, and enable an appropriate response. The afferent limb includes the monitoring, the recognition of patient’s deterioration and the activation of the emergency team.The aim of this study is to describe the dynamics of the afferent limb, focusing on the evidence about early detection of the clinical deterioration in a general ward.