The relation between Bobbio and the theme of fundamental rights is complicated, reflecting the complicated relation that he had with natural law theory. What suggests retracing the salient points of Bobbio's thought on the theme of rights and natural law are certain of his unexpected remarks that appear in the introduction to the monograph by Peces Barba devoted to the theory of fundamental rights. After declaring the closeness of his theoretical positions to those upheld by the Spanish author, Bobbio proceeds to a sort of recapitulation of his own theses, followed, however, by some statements that seem to contradict the premises, as in a sort of 'self-clarification.' How can these statements be reconciled with his previous position? Do we witness a discontinuity in Bobbio's theory of human rights? A passage from a monist theory to a dualistic or integral theory?