Interlinking Ontology for Biological Concepts (IOBC) contains approximately 80,000 biological concepts such as biological phenomena, diseases, molecular functions, gene products, chemicals, and medical cares, and approximately 20,000 related concepts such as earth science and environmental science. The concepts are structured by thirty-five relations such as has function, has role, has quality, and precedes. Each concept has both of English and Japanese labels. For further information including the developmental method, see papers in the PUBLICATIONS PAGE of BioPortal (http://purl.bioontology.org/ontology/IOBC). The license for this ontology is specified in the Creative Commons Attribution-NonCommercial 4.0 International. If you use data from this ontology, please be sure attribute this ontology as follows: "Interlinking Ontology for Biological Concepts © National Bioscience Database Center licensed under CC Attribution-NonCommercial 4.0 International".