It is common for constipation to occur following severe spinal cord injury (SCI). Although a bowel management program including a high fibre diet is an integral part of rehabilitation, the effect of a high fibre diet on large bowel function in SCI has not been examined. The aims of this study were to assess the nutrient intake of SCI patients, to determine baseline transit time, stool weight and evacuation time and to assess the effect of addition of bran on large bowel function. Eleven subjects, aged 32 +/- 10.5 years participated in the study. The level of injury ranged from C4 to T12; only one patient had an incomplete injury. Baseline mean energy intake was 7823 +/- 1443 kJ/d, protein intake 93 +/- 21 g/d, carbohydrate intake 209 +/- 39 g/d and mean dietary fibre intake 25 +/- 8 g/d. Mean baseline stool weight was 128 +/- 55 g/d and bowel evacuation time was 13 +/- 7.4 min/d. Three subjects who consumed < 18 g dietary fibre/d had low stool weights of 60-70 g/d and two had very delayed transit times that were too slow to enable quantitation. Mean mouth to anus transit time was 51.3 +/- 31.2 h, mean colonic transit time 28.2 +/- 3.5 h, right colonic transit time 5.9 +/- 4.5 h, left colonic transit time 14.5 +/- 5.2 h and rectosigmoid colonic transit time 7.9 +/- 5.6 h. Following the addition of bran, dietary fibre intake significantly increased from 25 g/d to 31 g/d (P < 0.001). However, the mean colonic transit time increased from 28.2 h to 42.2 h (P < 0.05) and rectosigmoid colon transit time increased from 7.9 to 23.3 h (P < 0.02). Stool weight, mouth to anus, left and right colon transit time and evacuation time did not change significantly. Results of this study suggest that increasing dietary fibre in SCI patients does not have the same effect on bowel function as has been previously demonstrated in individuals with 'normally functioning' bowels. Indeed the effect may be the opposite to that desired. This preliminary study highlights the need for further research to examine the optimal level of dietary fibre intake in SCI patients.