Note: Transesterifications commonly occur during polycondensations to form polyesters.

Examples: The reactions of an ester group with a hydroxy group to give a new ester group plus a new hydroxy group (alcoholysis), of an ester group with a carboxylic acid group to give a new ester group plus a new carboxylic acid group (acidolysis), and of an ester group with another ester group to interchange substituents are all examples of transesterification.