Measurements of the transverse extensional compliance S-11 of highly oriented films of two liquid-crystal copolyesters are reported over a wide range of temperature and frequency. These results are compared with measurements of the shear compliance S-44 to show that there is a simple linear relationship between S-11 and S-44 over a wide temperature range. Models based on stiff fibres or on laths embedded in an isotropic incompressible matrix are advanced. These are instructive in providing some physical understanding on the basis that S-11 is determined by shear within the structure.