The concept of futility has often been invoked to justify abstention from treatment and decisions such as 'do not attempt resuscitation' (DNAR). In this capacity, futility has played an important part in the development of several sets of official clinical guidelines. In this paper, we examine the nature of futility and question whether it is a sufficiently robust concept to meet the ethical and clinical demands placed upon it. Although the concept of futility promises simplicity, it cannot stand alone as a satisfactory framework for clinical decision-making. Practitioners and policy makers should be cautious about their use of the concept.