A metathesis condensation process was applied for the synthesis of double cyclic, 8-shaped poly(THF)s. Thus, first, a cyclic poly(THF) having an allyl group, 1, was subjected to the intermolecular metathesis condensation. The bimolecular condensation reaction was found to proceed in the presence of a Grubbs catalyst, while with noticeable concurrent reactions. Alternatively, a twin-tailed tadpole, i.e., "a ring with two branches" structure, poly(THF) having tail-end allyl groups, 2, and a kyklo-telechelic poly(THF) having two allyl groups at opposite positions, 3, were prepared for the intramolecular metathesis condensation. The unimolecular reactions proceeded effectively even under dilution of the polymer concentration at 0.2 g/L to produce the corresponding 8-shaped poly(THF)s. These products were unequivocally characterized by means of H-1 NMR, SEC, and MALDI-TOF MASS techniques.