Résumé : The W+W− and ZZ production cross sections are measured in proton-proton collisions at s=8TeV with the CMS experiment at the LHC in data samples corresponding to an integrated luminosity of up to 5.3fb−1. The measurements are performed in the leptonic decay modes W+W−→ℓ′νℓ″ν and ZZ→2ℓ2ℓ′, where ℓ=e,μ and ℓ′(ℓ″)=e,μ,τ. The measured cross sections σ(pp→W+W−)=69.9±2.8(stat.)±5.6(syst.)±3.1(lum.) pb and σ(pp→ZZ)=8.4±1.0(stat.)±0.7(syst.)±0.4(lum.) pb, for both Z bosons produced in the mass region 60