  Identification of gravitationally lensed Gamma Ray Bursts (GRBs) in the BATSE
4B catalog can be used to constrain the average redshift $ < z >$ of the GRBs.
In this paper we investigate the effect of evolving lenses on the $< z >$ of
GRBs in different cosmological models of universe. The cosmological parameters
$\Omega$ and $\Lambda$ have an effect on the $< z >$ of GRBs. The other factor
which can change the $< z >$ is the evolution of galaxies. We consider three
evolutionary model of galaxies. In particular, we find that the upper limit on
$< z >$ of GRBs is higher in evolving model of galaxies as compared to
non-evolving models of galaxies.
