Hemihomonyms (same nomina which are used for taxa from different nomenclature jurisdictions) are an overlooked but genuine nuisance in biological nomenclature. We compiled the first list of hemihomonyms for nomina in bacteriological, botanical and zoological nomenclatures and prepared an on-line database, the "Hemihomonym database" or HHDB (<http://herba.msu.ru/shipunov/os/homonyms/index.php>). HHDB now includes 1164 nomina, including 12 triple hemihomonyms. A simple suffix-based solution (like "Oenanthe (z)" for Oenanthe in zoology) could be used in case of hemihomonymy. More effort should be afforded towards the resolution of long-standing nomenclature confusing situations such as hemihomonymy, including regarding the nomina of higher taxa, nomina of intermediate ranks and ambiregnal nomina.