In this article, I summarise the ontological theory of informational privacy (an approach based on information ethics) and then discuss four types of interesting challenges confronting any theory of informational privacy: (1) parochial ontologies and non-Western approaches to informational privacy; (2) individualism and the anthropology of informational privacy; (3) the scope and limits of informational privacy; and (4) public, passive and active informational privacy. I argue that the ontological theory of informational privacy can cope with such challenges fairly successfully. In the conclusion, I discuss some of the work that lies ahead.