An enhancement for the eta production in proton-neutron collisions as compa
red with that in proton-proton scattering has been recently observed, We pr
esent a calculation for the production cross section, in proton-neutron col
lisions near threshold, within instanton model for the QCD vacuum and show
that a specific flavor dependent nonperturbative quark-gluon interaction re
lated to instantons is able to explain the observed enhancement. (C) 2000 P
ublished by Elsevier Science B.V. All rights reserved.