  We present a study of jet production in association with W and Z bosons in
proton-proton collisions at a centre-of-mass energy of 7 TeV using the full
2010 data set collected by CMS corresponding to an integrated luminosity of
(35.9 +/- 1.4) inverse picobarn. We report the measurement of ratios s(V + >= n
jets)/s(V) and s(V + >= n jets)/s(V + >= (n - 1) jets), where V represents
either a W or a Z, s stands for the cross section and n stands for the number
of jets.
