To assess the effect of fasting and eating on estimates of apparent diffusion coefficient (ADC) in the livers of healthy volunteers using a diffusion-weighted magnetic resonance imaging (DW-MRI) protocol with b-values of 100, 500 and 900 s/mm(2) in a multicentre study at 1.5 T.Twenty volunteers were scanned using four clinical 1.5 T MR scanners. Volunteers were scanned after fasting for at least four hours and after eating a meal; the scans were repeated on a subsequent day. Median ADC estimates were calculated from all pixels in three slices near the centre of the liver. Analysis of variance (ANOVA) was used to assess the difference between ADC estimates in fasted and non-fasted states and between ADC estimates on different days.ANOVA showed no difference between ADC estimates in fasted and non-fasted states (p = 0.8) nor between ADC estimates on different days (p = 0.8). The repeatability of the measurements was good, with coefficients of variation (CV) of 5.1\% and 4.6\% in fasted and non-fasted states respectively.There was no significant difference in ADC estimates between fasted and non-fasted measurements, indicating that the perfusion sensitivity of ADC estimates obtained from b-values of 100, 500 and 900 s/mm(2) is sufficiently low that changes in blood flow in the liver after eating are undetectable beyond the variability in the measurements. Advances in knowledge: Assessment of the effect of prandial state on ADC estimates is critical, in order to determine the appropriate patient preparation for biological validation in clinical trials.