Monomers used for the synthesis of terephthalate polyesters have been prepared starting from renewable resources. In particular, dimethyl terephthalate was synthesised starting from bio-limonene while butanediol was synthesised starting from bio-succinic acid. Using these bio-monomers it was possible to synthesise polyesters with the same chemical structure and molecular weight of commercially available polymers. Moreover, the polymers obtained from bio-based monomers, present the same thermal properties of the polyesters obtained using petrol-derived monomers. A poly(butylene terephthalate) completely obtained from renewable resources was also synthesised. The radiocarbon and isotope mass spectroscopy analysis confirmed that this polyester contains 94 ± 3% of bio-based material.