A questionnaire, requesting information about the number of irritable bowel syndrome (IBS) patients referred to gastro-intestinal clinics and the involvement of dietitians in their treatment, was sent to 43 large hospitals of which 31 (72%) were returned. Forty high fibre diet sheets used for IBS by dietitians were analysed for content and design. Only a small proportion of patients referred to hospital saw a dietitian and they were rarely given a follow-up appointment. Diet sheets varied in their standard of presentation and possible interpretation. In an investigation of patients with IBS, 73 were managed on a high fibre diet in three groups: group A had repeated dietetic advice from a senior grade dietitian, group B had a single interview with the dietitian and group C received a diet sheet from a doctor without referral to the dietitian. Fibre intake of patients, and an age, sex matched control group, was assessed by a food frequency questionnaire at the beginning and end of the six month study. Patients also completed a 7-day weighed food inventory at the end. Symptomatic response was assessed blindly by the clinician using a standardised questionnaire and scoring system. On completing the study patients were questioned about the acceptability of the diet. There was no difference in fibre intakes of the three groups at the beginning or end of the study. Only 14 patients achieved a daily intake of 30g during the week they weighed their food. The majority of patients found the diet acceptable. The consumption of breakfast was the food habit which appeared to be of most benefit. There was a general improvement in all symptoms regardless of the amount of fibre ingested. However, larger fibre intakes were associated with improvements in specific symptoms, namely hard stools, constipation, urgency, mucus and watery stools.