Two conditions are commonly taken to constitute an obligation of confidentiality: information is entrusted by one person to another; and there is an express understanding that this will not be divulged. This conception of confidentiality, however, does not match much of the practice of health care. Health care practitioners would, for example, hold themselves to be under an obligation of confidentiality in situations where neither of these conditions obtain. The discussion proposes, therefore, two additional grounds for confidentiality. This is in (...) order to clarify, in general terms, the scope of this obligation (i.e. to clarify at what point confidentiality can be said to have been broken). The ‘limits of confidentiality’, it is argued, are set by the wishes of the client or, where these are not known, by reference to those whose right and need to know relate to the care of the client. Anonymous references to the client outside this limit may not be breaches of confidence; whether they are or not depends, it is suggested, on if such reference is responsible. (shrink)