The stream is formed in a place called ponte dei Passi from the union of three streams flowing down from the area of Monte Monega (Ligurian Alps): rio Teroselli, rio Giure and rio Conché. The Giara di Rezzo flows eastwards with a windy and recessed course, flanked by provincial road nr.17 Passo Teglia-Rezzo, which runs on its left high on the creek. While in comune of Pieve di Teco the Giara is trespassed by the former national road nr.453 della Valle Arroscia (nowadays provincial road nr.453) and a little further from the national road nr.28 del Colle di Nava. It ends joining the Arroscia from its right hand il Case Paperera, at around 215 m of elevation.