Representing experimental variables with EFO

The Experimental Factor Ontology (EFO) provides a systematic description of many experimental variables available in EBI databases, and for external projects such as the NHGRI GWAS catalogue. It combines parts of several biological ontologies, such as anatomy, disease and chemical compounds. The scope of EFO is to support the annotation, analysis and visualization of data handled by the EBI Functional Genomics Team. We also add terms for external users when requested. If you are new to ontologies, there is a short introduction on the subject available and a blog post by James Malone on what ontologies are for.


Browse EFO at NCBO BioPortal (external) or in EBI's OLS. You can also search EFO using the search box, above.


Download the latest release of EFO in OWL format. There is an OBO format version and an inferred OWL view. Read the latest Release Notes.


We provide tools to support the development and use of EFO such as Bubastis, an ontology diff tool, and Semantic Web work. See the complete list of tools.


Read more about EFO or see the Frequently Asked Questions. You can also read about ontologies in James Malone's blog.


Submit new terms or report bugs using our JIRA ticket system. You can also join the mailing list.


You can email James Malone directly with any questions or email the EFO list. The license for using EFO can be found here.