CERN-LHC. Measurement of total and fiducial inclusive W and Z boson production cross sections in pp collisions at sqrt(s) = 8 TeV. Electron and muon final states are analyzed in a data sample collected in 2012 with the CMS detector corresponding to an integrated luminosity of 18.2 +- 0.5 inverse picobarns. The measured total inclusive cross sections times branching fractions are SIG(P P --> W X) * BR(W --> LEPTON NU) = 12.21 +- 0.03 (stat.) +- 0.24 (syst.) +- 0.32 (lum.) nb and SIG(P P --> Z0 X) * BR(Z0 --> LEPTON+ LEPTON-) = 1.15 +- 0.01 (stat.) +- 0.02 (syst.) +- 0.03 (lum.) nb for the dilepton mass in the range of 60 to 120 GeV. Ratios of cross sections are reported with a precision of 2%.