Recent international guidelines about emergency situations (ILCOR / ERC) pointed to the need of the whole "chain of survival". ALS, Advanced Life Support (the last and "medical" part of the chain ) is important and influences survival rate. If no doubt exists about "what" and "when" to do in such situations, there is no consensus in industrialized countries about "who" should be in charge of such out-of-hospital acute diagnosis and treatment: emergency physicians, emergency nurses, emergency medical technicians (EMT), other "new" professionals ? ... A description of the MICU system in Belgium is given.