Cyclic oligomers of tetraethyleneglycol succinate [O(CH2CH2O)(4).CO.(CH2)(2).CO](x) were prepared by a ring-chain reaction. The cyclic products were characterized in full. Cyclic oligomers with up to eight repeal units were fractionated using preparative gel permeation chromatography to give narrow molar mass fractions with polydispersities of 1.03. The fraction consisting of the monomeric ring only was found to crystallize readily, enabling its X-ray crystal structure to be determined.