  To any left system of diagram categories or to any left pointed derivateur
(in the sense of Grothendieck) a K-theory space is associated. This K-theory
space is shown to be canonically an infinite loop space and to have a lot of
common properties with Waldhausen's K-theory. A weaker version of additivity is
shown. Also, Quillen's K-theory of a large class of exact categories including
the abelian categories is proved to be a retract of the K-theory of the
associated derivateur.
