There is compelling evidence that despite growing research into the complex neurophysiology of pain, the development of acute pain services, increasing educational interest in pain management and the proliferation of literature, many patients continue to suffer from unrelieved acute pain while in hospital. Educational efforts to bring about a change in practice have been relatively unsuccessful or slow to have real impact. Although it is still recognized that poor knowledge of pain control by all healthcare professionals is the major barrier to improving pain management, contemporary studies show that other, more subtle barriers can just as effectively inhibit a timely and effective response to patients' reports of pain. These barriers are not just the ones created by poor knowledge, myth and misconception; the most powerful barriers to change may be the invisible institutional barriers that can be entrenched within hospital policies and nursing rituals.