  We compute the light and strange quark masses m_l = (m_u+m_d)/2 and m_s,
respectively, in full lattice QCD with N_f=2 flavors of light dynamical quarks.
The renormalization constants, which convert bare quark masses into
renormalized quark masses, are computed nonperturbatively, including the effect
of quark-line disconnected diagrams. We obtain m_l=4.7(2)(3) MeV and
m_s=119(5)(8) MeV in the MSbar scheme at the scale 2 GeV.
