Vanhanen was elected to the Finnish Parliament (Eduskunta) in 1991. As a member of Parliament he was interested in ecological issues. For instance, Vanhanen spoke against the building of a fifth nuclear power plant in 1992, at the same time as serving on the board of electricity corporation Fortum. He served on the Parliamentary Environment Committee 1991–1995, and was chair of the Parliamentary Grand Committee 2000–2001. He was vice-chair of the Centre Party Parliamentary group 1994–2001, and Deputy Chairman of the Centre Party 2000–2003.