Astragalus neo-assadianus (Fabaceae), a new species endemic to Iran, is described and illustrated. This species belongs to A. sect. Alopecuroidei and is distinct and interesting among the Iranian species. It is confined to the northeastern part of Iran (Khorasan Province) and only known from a single collection close to the Turkmenistan frontier. (C) 2003 The Linnean Society of London.