Provides a database of human disease orthologs. OrthoDisease contains 2935 distinct human disease phenotypes from OMIM, mapped to 2313 out of 21 673 human genes and their orthologs in 99 other species from InParanoid. It is possible to search for orthologs of genes involved in particular diseases, in one or all model organisms, as well as to list all disease gene ortholog groups that exist between human and a particular species. Furthermore, the web server provides gene identifier, OMIM number and free text search options. Additionally, the download view allows the user to download all disease gene ortholog groups between human and another species as a file. Each disease gene ortholog group in OrthoDisease consists of the seed ortholog pair and, possibly, a set of genes inparalogous to the seeds. For each gene in the group, an inparalog score is provided that corresponds to the certainty of its inclusion.