Complete repertoires of molecular activity in and between tissues provided by new high-dimensional "omics" technologies hold great promise for characterizing human physiology at all levels of biological hierarchies. The combined effects of genetic and environmental perturbations at any level of these hierarchies can lead to vicious cycles of pathology and complex systemic diseases. The challenge lies in extracting all relevant information from the rapidly increasing volumes of omics data and translating this information first into knowledge and ultimately into wisdom that can yield clinically actionable results. Here, we discuss how molecular networks are central to the implementation of this new biology in medicine and translation to preventive and personalized health care.