CERN-LHC. The production of a W boson decaying to (e nu) or (mu nu) in association with a W or Z boson decaying to two jets is studied using 4.6 fb-1 of proton-proton collision data at sqrt(s) = 7 TeV recorded with the ATLAS detector at the LHC. The combined WW+WZ cross section is measured with a significance of 3.4 sigma. Two cross sections are measured, a fiducial and a total cross section. The cross sections are measured assuming the SM ratio between the WW and WZ cross sections. The fiducial cross section is measured for the combined WW+WZ process, with the di-bosons decaying to (lepton nu jet jet), summed over the (e nu) and (mu nu) channels, in the following fiducial region: pT of lepton > 25 GeV eta of lepton: |eta|<2.47 Transverse mass of leptonically-decaying W: mT>40 GeV Two jets with pT>25 GeV and |eta|<2.0, with |DeltaR(jet,lepton)|>0.5. Leading-pT jet must have pT>30 GeV. Veto events with more than 2 jets having pT>25 GeV and |eta|<2.8. MET>30 GeV The two selected jets must have |eta(j1,j2)|<1.5 Dijet-mass must satisify: 25<m(jj)<250 GeV If pT(jj)<250 GeV, then jets must be separated by DeltaR(j1,j2)>0.7 Azimuthal angle between MET direction and leading-pT jet: |DeltaPhi(MET,j1)|>0.8 In the fiducial region definition, the jets are generator-level jets, reconstructed from all stable particles excluding the decay products from leptonically-decaying W/Z bosons, using the anti-kT algorithm with R=0.4. The MET is defined as the momentum of the neutrino from the leptonically-decaying W. A total WW+WZ cross section measurement is also quoted, which is extrapolated from the fiducial region to the full WW+WZ phase-space.