The concept of a QTAG-module MR
was given by Singh [8]. The structure theory of such
modules has been developed on similar lines as that of torsion abelian groups. If a module MR is such
that M⊕M
is a QTAG-module, it is called a strongly TAG-module. This in turn leads to the concept of a
primary TAG-module and its periodicity. In the present paper some decomposition theorems for those
primary TAG-modules in which all h-neat submodules are h-pure are proved. Unlike torsion abelian
groups, there exist primary TAG-modules of infinite periodicities. Such modules are studied in the last
section. The results proved in this paper indicate that the structure theory of primary TAG-modules of
infinite periodicity is not very similar to that oftorsion abelian groups.