Reinforced autoclaved aerated concrete (RAAC) panels are widely used in mainland Europe. The experience in the UK has been rather mixed. Some serviceability problems have been encountered with some panels designed and built before 1980. A new European Standard covering prefabricated RAAC components is about to be published. This paper describes: Concerns raised about the performance of RAAC roof panels designed before 1980, laboratory testing of RAAC roof panels after some 20 years of service,and newly fabricated panels, some mechanisms that potentially influence the observed in-service behaviours, new design guidance contained in prEN 12602, and testing RAAC panels fabricated to the new design guidance. This paper does not apply to beam-and-block floors or walls that contain autoclaved aerated concrete blocks. This paper is a synposis of a more detailed report (BR445). 8 pages.