Iitti (Swedish:Itis) is a municipality of Finland.
It is located in the province of Southern Finland and is part of the Kymenlaakso region. The municipality has a population of 6,892 (31 March 2016) and covers an area of 687.08 square kilometres (265.28sqmi) of which 97.27km (37.56sqmi) is water. The population density is 11.69 inhabitants per square kilometre (30.3/sqmi).