Sejm ekstraordynaryjny

Sejm ekstraordynaryjny, sejm nadzwyczajny (special sejm) was a kind of sejm in pre-partition Polish–Lithuanian Commonwealth. It could be convened by the King in special occasions (e.g. war) for two or three weeks.

In 1637 Rejm Walny prohibited convening sejm ekstraordynaryjny.