Biological processes occur on a variety of temporal and spatial scales. To gain a comprehensive understanding of the human body, its anatomy, physiology, and pathologies need to be studied simultaneously at multiple levels, ranging from individual molecules and cells to the full organism. Computational modeling makes it possible to simulate such complex multi-scale systems, investigate specific mechanisms in a highly controlled manner, and analyze the importance of given parameters under strictly defined assumptions.The IT’IS Foundation develops in silico methods to study the mechanisms and dynamics of highly complex biological processes, to design and optimize medical devices and methodologies, and to perform treatment planning. Our research efforts focus, in particular, on the modeling of both internal and external physical factors that affect human physiology, including electromagnetic fields (e.g. MR safety assessments), tissue heating and cooling (e.g. hyperthermia and ablation), acoustics in biology (e.g. focused ultrasound/pressure waves), biofluid dynamics (e.g. blood flow and aneurysm), biomechanics (e.g. bone, ligaments, and arterial walls), and dynamic tissue models (e.g. nerve models and tumor growth). The solvers we develop are integrated in the Sim4Life platform, a multi-physics platform that is specifically tailored for computational life sciences and designed to interface with our Virtual Population. The Virtual Population is a set of high-resolution numerical whole-body models of humans that can be used for a variety of applications, ranging from electromagnetic dosimetry to the assessment of the effect of anatomical variability on diagnostic and therapeutic outcomes. These models are accompanied by a database of tissue properties, which we continuously update and enhance. Our goal is to provide the research community with tools to individually optimize diagnosis, medication, treatment planning, devices, and therapy.