Biocomposites were successfully prepared by reinforcing polylactic acid with flax fibres (PF). To improve the interfacial adhesion between the matrix and the fibres, amphiphilic compounds as additives were introduced. Structural and thermal characterisations of the PF were performed by Fourier transform infrared spectra, differential scanning calorimetry and thermogravimetric analysis. The interfacial adhesion between the fibres and the matrix was visually assessed from the SEM images of fractured specimens. Dynamic mechanicalthermal analysis was performed to evaluate the damping behaviour of the composites and thereby to interpret the interfacial adhesion between fibres and the matrix. It was observed that in the case of mandelic acid, particles/spheres were generated, resulting in effective stress transfer from the matrix resins to flax fibres, thereby increasing the storage modulus and impact strength of the composites. Mechanical properties and the water uptake of the composites with amphiphilic additives have also been reported.