The CHAIMELEON repository is expected to be used throughout the European Union as a common infrastructure that complies with all ethical and safety regulations of the countries involved. Its development builds on partner’s experience (e.g. PRIMAGE repository for paediatric cancer and the Euro-BioImaging node for Valencia population, by HULAFE; the Radiomics Imaging Archive by UM; the national repository DRIM AI France, the Oncology imaging biobank by UNIPI). Clinical partners and external collaborators are populating the Repository with multimodality (MR, CT, PET/CT) imaging and related clinical data for historic and newly diagnosed lung, prostate and colorectal cancer patients. The project aims to incorporate about 40,000 cases in the repository, which will be contributed by eight clinical partners. In addition, in order to demonstrate the universality of the models developed, external collaborators will be sought to contribute more medical images and clinical data to the common repository.