The 'fourth hurdle' is commonly described as what has to be done to gain market access and reimbursement for a pharmaceutical, medical technology, or biotech product. Demonstrating to regulatory agencies just a product's safety, efficacy, and quality (the first three hurdles) is no longer sufficient. Manufacturers must often now demonstrate both clinical effectiveness (Is the new product better than currently available alternatives, including no treatment?) as well as cost-effectiveness (Is the product good value for money?) in order to assure success in the marketplace. In the last few years there have been a number of governmental and non-governmental agencies constituted for fourth hurdle reviews and recommendations to governments and other funding and reimbursement agencies. The National Institute for Clinical Effectiveness (NICE) in the UK, although not the first such group, is arguably the most visible and influential. This paper describes the NICE review process in detail, as well as the expected substantial impact of fourth hurdle reviews on drug development and clinical trials. Potential uses of databases and modelling in fourth hurdle reviews are also explored.