Sysmä is a municipality of Finland. It is situated in the Päijät-Häme region. The municipality has a population of 3,496 and covers an area of 936.18 square kilometres of which 269.14 km2 is water. The population density is 5.24 inhabitants per square kilometre. Neighbouring municipalities are Asikkala, Hartola, Heinola, Kuhmoinen, Luhanka, and Padasjoki. The municipality is unilingually Finnish. Itä-Häme newspaper is established in Sysmä.