Finally, the $\ell^+\ell^-{\rm H}$ final state and the distribution of the mass recoiling against the lepton pair can also be used to directly measure the invisible decay width of the Higgs boson, in events where the Higgs boson decay products escape undetected. With the TLEP data at 240 GeV, the Higgs boson invisible branching fraction can be measured with an absolute precision of 0.25\%. If not observed, a 95\% C.L. upper limit of 0.5\% can be set on this branching fraction. 