Vibration signal measurements were performed on a commercial scale grinding process operated at LKAB. Three channels of mechanical vibration signals from the axial, horizontal and vertical directions, and one channel of acoustic signal at the centre of the abrasion zone outside the ball mill shell, were picked up, digitised and processed using a personal computer. The feed rate, power draw, pulp temperature were recorded automatically by the process control system while material samples of mill feed and product were taken for determination of particle size distribution and pulp density during signal acquisition. The particle size distributions, time-domain waveforms and power spectra were illustrated and discussed. By multivariate data analysis, close relationships were established between grinding parameters and the pattern of vibration signals. The results show that vibration signal analysis could be used to monitor grinding parameters for industrial scale ball mills.