The 27-year-old arrived at Leverkusen in 2004 from hometown club St Gallen,
but he has rejected the club's offer of a new contract and will be moving on.
'Tranquillo has turned down our offer and he will leave us on June 30,' Bayer
general manager Wolfgang Holzhauser said.
'This is very regrettable because we wanted to extend his contract, but we
could not reach an agreement financially.'
It is unclear whether or not Barnetta already has a new club lined up, and he
leaves Leverkusen after a season that saw him make only seven league
appearances due to a serious knee injury.