This study assessed the reproducibility of a previously developed diagnostic test using a macrogol stimulus and MRI measures to assess colonic motility. This test was performed twice on healthy volunteers and the results were compared. The data showed some variability across visits representing both variability in baseline data and the physiological response of the colon to the stimulus. Correlation data suggested that although intra-subject variability existed the maximum measured MRI parameters all increased post stimulus. This colonic stimulus test allows us greater insight into potential pathologies behind GI disorders and as such may be of value here.