2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/229805The roles of massive neutrinos in cosmology -- in leptogenesis and in the evolution of mass density fluctuations -- are reviewed. Emphasis is given to the limit on neutrino mass from these considerations.Plenary talk given at NuFact05, Frascati, 21-26 June 2005High Energy Physics - Phenomenologytext