Oja

Oja may refer to:


 * Oja (river), river in La Rioja, Spain
 * Oja (surname), an Estonian and Finnish surname
 * 5080 Oja, main-belt asteroid
 * Ōja Station, railway station in Hashikami, Japan
 * Oja's rule, a model of properties of neurons in the brain
 * "Oja", a 2019 song by Reminisce
 * Ọjà, musical instrument of the Igbo people