The río Ocosito (Spanish pronunciation: [okoˈsito]) is a river in Guatemala. The river's sources are located in the Sierra Madre mountain range in Quetzaltenango. It flows southwards to Retalhuleu and then west to the Pacific Ocean. The river is 107 kilometres (66 mi) long. The Ocosito river basin covers an area of 2,035 square kilometres (786 sq mi).

• Map of Guatemala including principal rivers, from University of Texas