The importance of the evaluation of health care interventions (EHI) including formal health technology assessment (HTA) cannot be over-emphasised, as its results can inform and improve resource allocation decisions in all parts of the health care system, public and private. At present, fragmented and inefficient resource allocation processes are a universal problem and, as a consequence, patients are deprived of care from which they could benefit. Such outcomes are not only inefficient but also unethical. In this paper we focus on HTA, which emphasises the need to link evidence to policy and practice, but our conclusions can be applied to all types of EHI. There is a need for greater use of economic evidence within HTA. Four principle characteristics of HTA are discussed in this paper: types of knowledge and evaluation, and commissioning and knowledge utilisation. Policy-makers must invest in improving research and receptor capacities for producing and using knowledge, improve quality control, and invest in research into dissemination and implementation mechanisms. The potential of HTA is great, and its use has increased, but it remains largely unexploited in most countries. (C) 2002 Elsevier Science Ireland Ltd. All rights reserved.