Polylactic acid (PLA) oligomers as coupling agents have shown higher interfacial shear strength in phosphate based glass fibres/ PLA composites. To influence bonding on the glass fibre surface, short chain PLAoligomers with different end groups were used as coupling agents. The low molecular weight PLA with a sodium salt terminal group, a carboxylic acid end groupand also with one, two and five hydroxyl groups were produced and applied on the fibre surface through a condensation reaction. Mechanical properties of the sized fibres/PLA composites were found to be increased. XPS and TG analyses showed the presence of the coupling agents on the fibres surface. SEM analysis further confirms the presence of the agents.