Ruo

Ruo or RUO may refer to:


 * Ruo (state), a small vassal state during the Chinese Zhou Dynasty
 * Istro-Romanian language, spoken in Croatia (ISO 639 code = ruo)
 * Huang Ruo, a Chinese-born American composer
 * Ruo River, a tributary of the Shire River in Malawi and Mozambique
 * Ruo Shui, a large river of northern China
 * Emoh Ruo is a 1985 Australian comedy film
 * Ruo, Federated States of Micronesia, a village and municipality in the state of Chuuk
 * RUO, an abbreviation for "Research Use Only": designation for diagnostic products or reagents by the FDA