| Lake Veisiejis | |
| Location: | Lazdijai district, Lithuania |
| Coords: | 54.05°N 23.6°W |
| Inflow: | Zapsė |
| Pushpin Map: | Lithuania |
| Outflow: | 4 rivulets |
| Basin Countries: | Lithuania |
| Length: | 12.5km (07.8miles) |
| Area: | 7.652km2 |
| Depth: | 6.03m (19.78feet) |
| Max-Depth: | 33.8m (110.9feet) |
| Shore: | 41.13km (25.56miles) |
| Islands: | 13 |
Veisiejis Lake is in the Lazdijai district of southern Lithuania, about southwest of Veisiejai city. The lake is narrow, like a river, with sharp, high shores. Veisiejis Lake has 13 islands with a total area of . The lake connects with Lake Niedus.
Around the lake are the villages of Paveisiejai, Navikai, Gerveliai, Sapiegiškiai, Paveisininkai, Burbai, Palačionys, Purviniai, Subačiai, and Kalviai.
The Veisiejis lake had a surface area of until 1956, but after the construction of the Kapčiamiestis hydroelectric power station, Veisiejis joined with Nadorius and Uosis lakes.