There is a high demand for patient specific cardiovascular disease therapeutics. Paediatric cardiology, in particular, faces difficult challenges due to the evolving nature of a child's heart and vascular system. Comprehensive and accurate computer models reconstructed from patient specific data and simulated physical constraints are needed to help determine better and more reliably risk stratification to improve and personalized therapies, and ultimately to decrease morbidity and increase survival of patients.The Sim-e-Child project proposes to develop a grid-enabled platform for large scale simulations in paediatric cardiology, providing a collaborative environment for constructing and validating multi-scale and personalized models of a growing heart and vessels.The project will establish an international cooperation, by linking the EC funded Health-e-Child project with leading institutions such as the American College of Cardiology, Johns Hopkins University, Technical University of Munich, and Siemens Corporate Research. Sim-e-Child is an extension of the Health-e-Child platform that:•Interconnects the Health-e-Child database with new data from two prospective US multicenter studies•Enhances and expands the Health-e-Child heart with existing models of the aorta, aortic valve and mitral valve, and with computational fluid dynamics•Integrates the Health-e-Child Gateway and Case Reasoner with versatile tools for simulation workflow composition (iKDD) and sharing of scientific experiments (SciPort)The objective of the Sim-e-Child is to strengthen the impact of the Health-e-Child project by creating an international simulation and validation environment for paediatric cardiology, supported by integrated data repositories. The project will advance the state-of-the-art by providing comprehensive and patient specific models for the dynamic and longitudinal interactions occurring in the left heart, with a focus on the congenital aortic arch disease and repair.