Ruotsinpyhtää (Finnish pronunciation: [ˈruo̯tsimˌpyhtæː]; Swedish: Strömfors) is a former municipality of Finland.

Ruotsinpyhtää, Pernå and Liljendal were consolidated to Loviisa on January 1, 2010.

The municipality was bilingual, with majority being Finnish and minority Swedish speakers.

After the Treaty of Åbo in 1743 the border between Sweden and Russian Empire was drawn on the Ahvenkoski rapid, dividing Pyhtää between the two states.

In 1744 Jakob Forsell (later af Forselles) and Anders Nohrström bought the local ironworks, which was renamed Strömfors after their surnames.