  The contributions into radiative correction parameters S, T, U from the
scalar leptoquarks are calculated in the minimal gauge model with the
four-color quark-lepton symmetry. It is shown that the contributions into T and
U from the scalar leptoquark doublets are not positive definite. Using the
current experimental data on S, T, U the bounds on the scalar leptoquark masses
are obtained. In particular, the existence of the relatively light scalar
leptoquark with electric charge 2/3 is shown to be compatible with the current
experimental data on S, T, U.
