| Lygna | |
| Name Other: | Lyngdalselva Storåni |
| Subdivision Type1: | Country |
| Subdivision Name1: | Norway |
| Subdivision Type3: | County |
| Subdivision Name3: | Agder |
| Subdivision Type4: | District |
| Subdivision Name4: | Lister Region |
| Subdivision Type5: | Municipality |
| Subdivision Name5: | Lyngdal, Hægebostad |
| Length: | 82.2km (51.1miles) |
| Discharge1 Avg: | 35.9m3/s |
| Source1: | Øyvassheia |
| Source1 Location: | Hægebostad, Agder, Norway |
| Source1 Coordinates: | 58.6553°N 7.1164°W |
| Source1 Elevation: | 909m (2,982feet) |
| Mouth: | Alleen |
| Mouth Location: | Lyngdal, Agder, Norway |
| Mouth Coordinates: | 58.1422°N 7.0494°W |
| Mouth Elevation: | 0m (00feet) |
| Basin Size: | 667.08km2 |
Lygna or Lyngdalselva is a river in Agder county, Norway. The 82.2km (51.1miles) river runs from the mountains in northern Hægebostad municipality, through the Lyngdalen valley to the municipality of Lyngdal to its mouth at Alleen, where it runs into Lyngdalsfjorden. Lygna has a discharge of, and a drainage basin covering .[1] The river is called the Storåni north of the lake Lygne. The river passes the villages of Tingvatn, Snartemo, and Kvås as well as the town of Lyngdal.[2]