A number of techniques for measuring the hardness of wheat grains were compared. The relationships between different tests were examined, as well as the efficiency with which they separated varieties into hard and soft classes. These tests were done on a number of varieties grown under different environmental conditions. The effect of hardness on the milling quality of these wheats was also investigated. All tests for hardness considered were found to be closely related, with logarithmic relationships being more meaningful in some instances. Hardness had a considerable effect on the milling properties of the different varieties, with extreme hardness resulting in a marked drop in flour extraction.