We present SPOKE, an Open Knowledge Network (OKN) for Precision Medicine. The network spans from genomic, through the epigenomic, protein, tissue, organ and anatomy layers of the human body and its diseases; and beyond the body to exogeneous factors such as drugs, and environmental factors such as water contaminants. Derived from 45 very large scientifically accepted datasets, the network consists of about 45 million nodes and 75 million relationships, and continues to grow. Its application in precision medicine, and predictions of conditions such as Parkinson's disease per patient, are illustrated.