Following concerns expressed in the media in relation to the performance of hollow core slabs in fire, two full-scale fire tests were carried out at BRE's Large Building Test Facility at Cardington near Bedford. The objectives of the programme were to assess the adequacy of this form of construction in terms of the functional requirements of Approved Document B of the Building Regulations. This paper explains the background to the work, describes the test parameters in some detail and summarises the main test results and conclusions from the project.