Precise heavy-quark masses

We report on determinations of the running masses for charm- and bottom-quarks from deep-inelastic scattering reactions and for the top-quark from hadro-production of top-quark pairs. The running masses in the (MS) over bar scheme can be extracted with good precision at next-to-next-to-leading order in QCD. In the global fits to data the full correlations of the extracted mass parameters with the parton distributions in the proton and with the strong coupling constant alpha(s) are kept. For charm- and bottom-quarks the method provides complementary information on these fundamental parameters from hadronic processes with space-like kinematics. The measured top-quark mass is confronted with the Monte Carlo top-quark mass parameter determined from a comparison to events with top-quark decay products. The Monte Carlo mass is not identical with the pole mass. Its translation to the pole mass scheme introduces an additional uncertainty of the order of 1 GeV.