Abstract
By means of general kinematical arguments, the lifetime tau of a graviton of energy E for decay into gravitons is found to have the form tau(-1) = (1/EG) Sigma(j=1,2,...) c(j)(Lambda G)(j). Some recent, preliminary results of non perturbative simplicial quantum gravity are then employed to estimate the effective values of G and Lambda G. It turns out that a short lifetime of the graviton cannot be excluded.