The U20 SM-sarja ('Under-20 Finnish Championship Series') is the premier junior men’s ice hockey league in Finland. It was previously known as the A-nuorten SM-sarja ('Junior A Finnish Championship Series') during 1945 to 1991 and the Nuorten SM-liiga ('Junior Finnish Championship League') during 1991 to 2020. The league was founded by the Finnish Ice Hockey Association in 1945 and a Finnish Champion in men’s under-20 ice hockey has been named annually since the league’s inaugural season – with the exception of the 2019–20 season, in which the playoffs were cancelled due to the COVID-19 pandemic. Eighteen to twenty teams compete in the U20 SM-sarja regular season, which is played in a preliminary ranking stage followed by a divisional or group stage.