What is good prescribing? In this paper we will look at the kinds of criteria which are relevant to evaluating prescribing. In particular we wish to challenge, or at least re-frame, the picture of prescribing as an essentially technical process. In so doing we hope to indicate something more general about the power, and limitations, of technical rationality in health care, and to contribute something to work in health care technology assessment. Finally we hope this discussion will act as a stimulus towards a much needed revision of the way 'good' prescribing is defined by current policies, guidelines and protocols.