  We discuss the stability of multiquark systems within the recent model of
Glozman et al. where the chromomagnetic hyperfine interaction is replaced by
pseudoscalar-meson exchange contributions. In this model the (u,d) diquark S=0
I=0 is strongly bound (more than for the chromomagnetic interaction) and this
leads to a bound heavy tetraquark QQ\bar q\bar q where the light quarks are in
the S=0 I=0 configuration. We study the stability of other multiquark systems
as well.
