A device for measuring the mechanical properties of polymers in shear has been devised, built and tested. The type of deformation employed is that of simple shear of flat sheets and the displacements are measured using a Hall-effect extensometer. The method has been tested using isotropic samples of low-density polyethylene and the results for shear compliance are found to agree satisfactorily with those obtained from conventional extension tests. Continuous records of shear strain or compliance against time have been obtained, as have measurements of the variation of compliance with strain. The method is quick and simple and gives direct results for shear compliances, time dependences and strain dependences, the last two properties being very difficult to measure using conventional torsional techniques.