Health technology assessment (HTA) involves the systematic evaluation of healthcare technologies and the dissemination of assessment findings. Its main purpose is to provide objective information to support healthcare decisions and policy-making. This article provides a brief overview of HTA, covering availability of assessment reports, approaches used, relevance and reliability of assessments and the influence of HTA. HTA reports vary greatly in their scope and complexity, because of the range of questions considered and the needs of those who request advice on health technologies. A key to the reliability of an HTA report is its transparency. Explicit information should be provided on the question that is addressed, data used, approach to analysis, and any assumptions that are made. Effectiveness of HTA--the extent to which it influences decisions--will be highly dependent on how well assessment findings are disseminated.