In this essay I present Rawls's theory from a catholic perspective to treat the matter of if his conception on justice as 'fairness' is compatible or not with the social teaching of the Catholic Church. I will provide, in first place, a brief summary of his approach. In second place, analyzing more carefully the method and content of his theory, as his anthropologic implications, I will raise some objections against Rawls's conception. Supporting myself in this critique I will try to point out, in third place, the most important similarities and differences between Rawls's social justice conceptions and the Catholic Church's.