  We investigate the possibility of mixing between open and closed string
excitations in D-brane models with the fundamental string scale at the TeV. The
open string modes describe the Standard Model Higgs, while closed strings
describe graviscalars living in the bulk. This provides a string setup for
computing the Higgs-graviscalar mixing, that leads to a phenomenologically
interesting invisible width of the Higgs in low scale quantum gravity models,
as suggested previously by Giudice, Rattazzi and Wells.
