In discussions among nonphilosophers, the ethical argument from naturalness frequently comes up. “Of course, cloning should be banned—it is unnatural.” “Surely you cannot deny that homosexuality is unnatural (and hence it should be condemned).” “The immorality of gene technology is apparent because things like that do not happen in nature. Genes do not jump between species and crossbreeding produces infertile offspring.” Even those who come from a philosophical background can catch themselves thinking, “That is unnatural!” and finding grounds for suspicion from the thought. But what do we mean when we talk about (im)morality and (un)naturalness? What interpretations can be given to the ideas of natural and unnatural in ethical discussions? What are the implications of these interpretations? Are there good grounds for assuming that naturalness is morally better than its opposite?This paper was first presented at the Fourth International Bioethics Retreat in Paris, May 2001. I wish to thank the participants for their comments on my paper. This paper was produced as a part of the project Genes, Information, and Business, financed in 2000–2003 by the Academy of Finland.