  We study the effects on the leptonic asymmetries A_{FB}, A_{pol} and A_{LR}
coming from a model of compositeness. We consider the effects coming from the
self-energies and the vertex correction to $Z l^+ l^-$. Thus we use the
Altarelli parametrization of the oblique corrections. We get the asymptotic
limits of these corrections in terms of the parameters $(m^*, \Lambda, f, f')$
and we get bounds for the quotient $m^*/\Lambda$ with different values of $(f,
f')$. We conclude that both asymmetries produce bounds for such quotient when
$f'$ overweigth to $f$, and this fact is related with the breakdown of the
custodial symmetry.
