Unio

Unio may refer to:


 * Unio (bivalve), a genus of freshwater mussels
 * Unio (sternwheeler), a steamboat that operated in Oregon, United States, in 1861, before being renamed Union
 * UNI/O, an asynchronous serial bus
 * UNIO Satu Mare, a Romanian machine-building company
 * Utdanningsgruppenes Hovedorganisasjon or Confederation of Unions for Professionals, a national trade union center in Norway