Computer Assisted Medical Intervention (CAMI thereafter) is a complex multi-disciplinary field. It requires for example patient-specific models built from medical image analysis and reconstruction, image or mesh registration an efficient and trustworthy simulations. CAMI research requires the collaboration of experts in several fields as various as medicine, computer science, mathematics, instrumentation, signal processing, mechanics, modeling, automatics, optics,etc. CamiTK ( http://camitk.imag.fr ) is a specific modular framework that helps researchers and clinicians to collaborate in order to prototype CAMI applications by using the best knowledge and know-how during all the requested steps. CamiTK is an open-source, cross-platform generic tool written in C++ which can handle medical images, surgical navigations and biomedicals simulations. CamiTK’s general design is inspired by component-based software engineering (CBSE). Instead of building an application by adding features on existing code,CBSE intends to build a software by integrating, arranging or assembling pre-built software components. CamiTK shares the CBSE guiding principles: - reuse and do not reinvent the wheel, - assemble pre-built modules and components instead of adding codes where needed.