The ouguiya (sign: UM;Arabic: أوقية‎; currency code: MRU), also spelled "ougiya", is the currency of Mauritania. Each ouguiya constitutes five khoums (singular and plural in English, Arabic: خمس‎, meaning "one fifth"). As such it is one of two circulating currencies, along with the Malagasy ariary, whose division units are not based on a power of ten.

The current ouguiya was introduced in 2018, replacing the old ouguiya at a rate of 1 new ouguiya = 10 old ouguiya, which in turn replaced the CFA franc at a rate of 1 old ouguiya = 5 francs. The name "Ouguiya" (أوقية) is the Hassaniya Arabic pronunciation of "Awqiyyah" (أُوقِية), meaning "ounce".