We assume that Yukawa couplings of up and down quarks are related by Y
-u proportional to Y-d(2) at grand unification (GU) scale. Using the s
pecific ansatz for Y-d We Obtain the CKM matrix that is symmetrical at
the GU scale and two relations between the quark masses. Using three
specific models as illustrative examples for the evolution down to low
energies, we obtain a non-symmetric CKM matrix whose entries are in g
ood agreement with their measured values and two quark mass relations
at the m(t) scale: (m(u)/m(c)) = (m(d)/m(s))(2) and (m(c)/m(t)) = k(m(
s)/m(b))(2) with the coefficient k fixed from the renormalization grou
p (RG) evolution. (C) 1998 Elsevier Science B.V. All rights reserved.