  We calculate and analyze Z and W production in association with
quark-antiquark pair in k_T-factorization. Numerical calculations are performed
using the Monte Carlo generator CASCADE for proton proton collisions at LHC
energy. We compare total and differential cross sections calculated in
k_T-factorization approach with total differential cross sections obtained in
LO and NLO calculations in collinear factorization approach. We provide strong
evidence that some of the effects of the NLO and even higher order collinear
calculation are already included in the LO k_T-factorization calculation.
