Résumé : A search for the Higgs boson produced in association with a W or Z boson in proton-proton collisions at a center-of-mass energy of 7TeV is performed with the CMS detector at the LHC using the full 2011 data sample, from an integrated luminosity of 5 fb -1. Higgs boson decay modes to τ τ and WW are explored by selecting events with three or four leptons in the final state. No excess above background expectations is observed, resulting in exclusion limits on the product of Higgs associated production cross section and decay branching fraction for Higgs boson masses between 110 and 200 GeV in these channels. Combining these results with other CMS associated production searches using the same dataset in the H → γγ and H → bb̄ decay modes, the cross section for associated Higgs boson production 3.3 times the standard model expectation or larger is ruled out at the 95% confidence level for a Higgs boson mass of 125 GeV. © SISSA 2012.