The present paper describes the results of a round robin that has been performed to investigate the influence of particle shape on particle-size distributions measured with commercial particle-size analyzers. The commercial equipment based on the five kinds of measuring principle such as electrical sensing zone, laser diffraction and scattering, X-ray sedimentation, photosedimentation, and light-obscuration methods have been employed for analyzing blocky, flaky and rod-like ceramic particles. It is demonstrated that the particle shape has a strong influence on the particle-size distribution measured by the laser diffraction and scattering and by photosedimentation. The size range of rod-like particles is particularly wide when these methods are applied. It is also shown that the particle-size distributions of anisotropic samples measured by photosedimentation has a tendency to be remarkably scattered in the coarse-size range.