The Arieş is a tributary of Mureş River in Transylvania, Romania.

The Hungarian name "Aranyos" means "Golden" and it was first mentioned in 1177. The Romanian name (which means nothing in Romanian) derives from the name Aranyos. According to another opinion, "Arieş" means "Gold River" in Dalmatian which is thought to be very similar to the Dacian language. It is concluded that the Romanian name most probably derives from the Dacian name of the river.

The source of the river is in the Bihor Mountains part of the Apuseni Mountains. The Arieş is formed near the village of Mihoieşti at the junction of two headwaters: Arieşul Mare and Arieşul Mic. Its length is approximately 164 km. It flows through Alba and Cluj Counties and flows into the Mureş near the village of Gura Arieşului, which is close to the town of Luduş.

The towns of Câmpeni, Baia de Arieş, Turda, and Câmpia Turzii lie on the river Arieş. The upper valley of the river, Ţara Moţilor, is a beautiful rustic region and an important mining region (Roşia Montană), rich in gold, silver and uranium.

The following cities are situated along the river Arieş, from source to mouth: Turda and Câmpia Turzii.