This article shows a proposal to improve patient´s care time through the application of Lean Manufacturing methodology in an Adult Emergency Department of a Hospital in La Sabana de Bogotá, Colombia.The main problems observed are related to the excessive time that patients must wait for treatment compared to the standards established by the District Health Department.Firstly, the current state of the processes is registered and analyzed.After that the main factors that cause delays are identified and finally a methodology is proposed to improve the present situation.The results shown that the processes to improve are: inclusion in Triage (urgency classification system) and consultation, the process according to consultation and the patient exit order.The applicability of the proposal was evaluated through simulations using the Software Arena.The simulations show important improvements in patient`s waiting time and in consultation time.