  It has been recently suggested in hep-ph/9911535 and hep-ph/0006324 that the
fourth generation of leptons and quarks is not excluded by the precision
Z-boson measurements, provided that the mass of the fourth neutrino is around
50 GeV and that its mixing with the neutrinos of the first three generations is
negligibly small. We would like to note that in this case the decay rate of the
Standard Model Higgs boson into the pair of such neutrinos would be about two
orders of magnitude higher than than the Higgs to b-bbar rate. Thus, the
predominant decay mode of the Higgs would be invisible, which would require a
special strategy for its searches.
