  The mass of the top quark is a fundamental parameter of the standard model
(SM) and has to be determined experimentally. The D0 experiment at the Fermilab
Tevatron proton-antiproton collider with a centre-of-mass energy of 1.96 TeV
has measured the top quark in various channels. In this talk, I present the
most recent measurements of the top quark mass in the dilepton and lepton+jets
channels with up to 5.3 \fb\ as well as their combination, and give an outlook
on the final, most precise measurement of the top quark mass at D0.
