Seimėnai is a village in Trakai District Municipality, in Vilnius County, Lithuania. Seimėnai lies at 151 m above sea level. It has 40 inhabitants (2021). The nearest city is Vilnius, 29 km to the east. Among the landmarks around are Trakai Island Castle (6.6 km), Vilnius Cathedral (30 km) and National Museum of Lithuania (30 km).