Irene Roberts is Professor of Paediatric Haematology at the MRC Weatherall Institute of Molecular Medicine at the University of Oxford. She is an internationally recognised paediatric haematologist playing a key role in developing and implementing policy in this speciality. The most notable aspect of her academic career has resulted from her unique research in understanding haematopoiesis in early development and the associated breakthroughs in diagnosing and treating the haematological disorders arising in childhood; in particular, in Down syndrome. Research originating almost entirely from her laboratory provided the first robust evidence that trisomy 21 is the key abnormality initiating leukaemia in children with Down syndrome. This work now forms the basis for national and international guidelines for the management of infants and children with Down syndrome.