  We study systematically the possibility for realizing realistic values of
quark mass ratios $m_c/m_t$ and $m_s/m_b$ and the mixing angle $V_{cb}$ by
using only renormalizable Yukawa couplings derived from heterotic orbifold
models. We assume one pair of up and down sector Higgs fields. We show
realistic examples including hierarchical and democratic forms of Yukawa
matrices.
