The Ituí River is a river of the upper Amazon Basin. It traverses some 370 km of the Atalaia do Norte municipality in the Amazonas state of north-western Brazil. The Ituí is a left tributary of the Javary River. It drains a very low gradient, dropping hardly 100 m over its whole extent, which results in extensive meandering. The Rio Negro, Beija-flor and Branquinho are some of its western tributaries, while the Rio Novo is its main eastern tributary. Downstream it joins the Itaquai River to form the upper Solimões.