  While LOFAR and the SKA will enable the study of HI at the epoch of
reionization for the first time, expectations for the distribution of HI at
that redshift depend on our understanding of the cosmological HI mass density
at the present epoch and its variation with environment. We exploit a complete
optical diameter and HI flux limited sample of galaxies in the local universe
to derive a robust measurement of the HIMF for masses log(M / M_{Sun}) > 7.4
which takes into account the effects of local large scale structure.
