| Aso | |
| Source1 Location: | Monti Sibillini, near Foce |
| Mouth Coordinates: | 43.103°N 13.8422°W |
| Subdivision Type1: | Country |
| Length Km: | 63 |
| Source1 Elevation: | 950m (3,120feet) |
| Mouth Elevation: | 0m (00feet) |
| Discharge1 Avg: | 2.6m3/s |
| Basin Size Km2: | 242 |
The Aso (la|Helvinus)[1] is a 63km (39miles) river in the Marche region of Italy. For most of its course the river marks the boundary between the provinces of Ascoli Piceno and Fermo The river's source is in the Monti Sibillini, near Foce in the Comune of Montemonaco, at an elevation of 950m (3,120feet). The Aso flows through the settlements of Tofe, San Giorgio all’Isola, Illice, Piane, Comunanza, Montecchio, Madonna del Lago, Aso and Rubbianello before entering the Adriatic Sea at Pedaso, where it delivers a mean discharge of 2.6m3/s.