Sysmä is a municipality of Finland. It is situated in the Päijänne Tavastia region. The municipality has a population of and covers an area of km2 of which km2 is water. The population density is PD/km2. Neighbouring municipalities are Asikkala, Hartola, Heinola, Kuhmoinen, Luhanka, and Padasjoki. The municipality is unilingually Finnish. Itä-Häme newspaper is established in Sysmä. Sysmä is also a lake in Joroinen and another lake in Ilomantsi.