AbstractWe describe the preparation of telechelic OH‐terminated poly[(R)‐3‐hydroxybutyric acid] (PHB) and poly{[(R)‐3‐hydroxybutyric acid]‐co‐[(R)‐3‐hydroxyvaleric acid]} (PHB/HV), on a semi‐preparative scale, by a transesterification procedure from the high‐molecular weight polymers. The oligomers have well‐defined reactive end groups and are well suited for the preparation of high‐molecular‐weight block copolymers by chain extension.