| Alfenz | |
| Source1 Coordinates: | 47.1375°N 10.1563°W |
| Mouth Coordinates: | 47.1349°N 9.837°W |
| Subdivision Type1: | Country |
| Length: | ~ 26km (16miles) |
| Source1 Elevation: | 2640m (8,660feet) |
The Alfenz is a river of Voralberg, Austria.
The Alfenz is approximately long and the main river in the valley Klostertal. It originates from the confluence of the Flexenbach and the Rauzbach near Stuben. and flows in western direction. The river's flow created the Klostertal. The Alfenz flows into the Ill east of Bludenz.
Villages near the river include Klösterle and Dalaas. The S16 expressway (German: [[Arlberg Schnellstraße]]) runs alongside the river.
The origin of the Alfenz is close to the European watershed. The Alfenz belongs to the Rhine basin, while across the Arlberg to the east the water flows into the Danube. The Alfenz carries rocks from the Northern Limestone Alps that crop out north of the river and the Silvretta Crystalline which crops out in the south.