Steve-O has written a letter pleading for experimenting on chimpanzees to be banned.
The 'Jackass' star - whose real name is Stephen Glover - has sent a note to Democratic Party Senator Barbara Boxer begging her to pass the Great Ape Protection and Cost Savings Act through her committee and towards passage to help spare the animals from being subjected to ''cruel experiments'' in the US.
In the letter, he wrote: ''Many people know me as the guy who intentionally harmed himself over and over on the show 'Jackass'.
''But I am actually very serious about some things - including protecting chimpanzees and other animals from being intentionally harmed.
''Nearly 1,000 chimpanzees are locked up in laboratories in the United States. They have no choice about whether they will undergo painful, invasive procedures and be infected with deadly diseases. These individuals are smart and sensitive - and they suffer greatly in laboratories.''
The 37-year-old stunt performer has joined several celebrities including Alec Baldwin, James Franco and Ellen DeGeneres in pleading with Congress in support of the bill.
His letter continued: ''The Great Ape Protection and Cost Savings act already has widespread support in Congress and among constituents. But it needs to be moved through your committee and to the floor of the Senate as soon as possible. These chimpanzees have spent years or even decades in lab cages - we need to move quickly to give them peace.''