  High redshift radio galaxies (HzRGs) are key targets for studies of the
formation and evolution of massive galaxies. The role of dust in these
processes is uncertain. We have therefore observed the dust continuum emission
from a sample of z > 3 radio galaxies with the SCUBA bolometer array. We
confirm and strengthen earlier results, that HzRGs are massive starforming
systems and that submillimeter detection rate appears to be primarily a strong
function of redshift. We also observed HzRG-candidates which have sofar eluded
spectroscopic redshift determination. Four of these have been detected, and
provide evidence that they may be extremely obscured radio galaxies, possibly
in an early stage of their evolution.
