The company said a search for Mr Jenkins? successor was underway.
In a statement, Barclays deputy chairman Sir Michael Rake said he had ?reflected long and hard on the issue of group leadership?.
He said a ?new set of skills? was required at the head of the group.
The bank appointed Mr Jenkins as group chief executive in August 2012.
Barclays? chairman John McFarlane has been appointed executive chairman until Mr Jenkins? successor is appointed.