The synthesis of series of cyclic oligo(alkylidene isophthalate)s by the cyclo-depolymerisation of the corresponding linear polymers has been investigated and the yields of the various cyclic oligomers determined as a function of the polymer structure. With up to 15 ring atoms per repeat unit the main products are the cyclic dimers (up to 90% yield) with smaller amounts of the larger rings. When there are more than 16 ring atoms per repeat unit the main products are the cyclic monomers (up to 72% yield) with smaller amounts of the larger rings. Possible applications for such cyclic oligomers are discussed including their possible use as feedstocks for environmentally friendly entropically driven ring-opening polymerisations and as building blocks for novel polymeric structures.