The present-day patients have complex diseases that are responsible for the great increase of medical interventions, overcrowding in emergency departments and access to the wards, increased waiting times and length of stay, difficult discharge, increased readmission rate and finally increased mortality. By breaking the steps of the patients pathways it allows us to simplify the problems and to face the individual aspects of the complexity related to the management of patients in the hospital. One solution that has been growing in popularity is the rapid intensive observation of the patients in acute hospital setting within Internal Medicine wards. This model has been otherwise defined with different terminology, but the most widely used name is Acute Medical Unit (AMU). We describe the model of an AMU within an Internal Medicine department as proposed and adopted in Anglo-Saxon countries, the methods of clinical approach and the practical organisation of the units in close collaboration with the ED ward. Finally we report our experience at an Internal Medicine department in Padova and the initial results obtained during the first 4 months of the project. Our approach of intensive rapid observation of intermediate risk patients admitted from the ED led to a significant reduction in the duration of hospitalization, without increasing readmission rate after discharge and fatality rate. Factors significantly associated to a short hospital stay were a preserved function and a lower number of previous admissions to the hospital. Several gray zones in the realisation and management of the project were identified and the possible solutions are still matter of discussion and debate.