An integrative network encoding knowledge from millions of biomedical studies. Hetionet v1.0 consists of 47031 nodes of 11 types and 2250197 relationships of 24 types. Data was integrated from 29 public resources to connect compounds, diseases, genes, anatomies, pathways, biological processes, molecular functions, cellular components, pharmacologic classes, side effects, and symptoms. Hetionet was created for Project Rephetio, which aims to systematically identify why drugs work and predict new therapies for drugs. Hetionet network is accessible via a Neo4j Browser and is available for download in three formats: JSON, Neo4j and TSV.