RESUMEN
In this article, the author -a Bishop of the Catholic Church-discusses the similarities and differences between two sets of ethical values that may guide the behaviour of medical professionals towards their patients and society. One set derives from Biblical principles contained in the Old and New Testaments, mainly represented by the Ten Commandments and Christ's Prayer from the Mountain. These principles are shared by all Christian nominations and by the Jewish and Muslim religions. The second one, although intrinsically agnostic, is also focused in the human individual and the human society. Both streams obey a "natural morality" common to all humans: every individual should respect each one's conscience, should avoid doing to others what each one would not íike to receive, to do not lie, kill or rob, to obey the rules of family and society. The Biblical Ethics stresses the value of responsibility in human behaviour while Modern Ethics sets the point in authenticity. In spite of their differences, the sharing of crucial points and end goals should inspire medical professionals regardless their religious beliefs to follow a common set of ethical values and to remain united in pursuing it.