After World War II, the interest in medical ethics increased and several international codes defending patients rights appeared. Four pragmatic, non ideological and non religious principles were defined to analyze clinical ethical problems. Autonomy, the capacity of self management and to reach our own informed decisions; the informed consent is the way to accomplish this principle. Beneficence, the basic principle of medical acts, with the risk of being transformed in an extreme paternalism. A reinterpretation of beneficence equilibrates the rights of patients physicians. Non wickedness, first of all not to harm, a Hippocratic idea to prevent iatrogenesis and Justice, to maintain personal, social and political equity. These principles are a language, an ethical analysis methodology and give clues for our relationship with patients. They are a guide for personal analysis, reflection and change and show a collective and individual path to incorporate ethics to our daily work.