Confidentiality is an acknowledged duty of the nurse. It has foundations in ethics and has some legal force. There is also a more disingenuous reason for citing it as a duty: that it helps a group attain professional status. This may cause an over-zealous attitude towards confidentiality in some professionals. There are legal and ethical limits to confidentiality which can be seen clearly in cases which arise out of human immunodeficiency virus (HIV). Whilst these make it clear that there are limits, neither the law nor ethics can state precisely what those limits are. Broad guidelines may be possible but in the end much will depend on the discretion and wisdom of the individual nurse. This can be informed by discussion of cases and of the ethical underpinnings of confidentiality.