Clinical details of 30 Caucasian women suffering from the irritable bowel syndrome were analyzed. Dietary fiber intakes, stool transit time, and stool weights were compared between groups of differing bowel habit and no statistically significant differences were found. A significant correlation between the clinical severity and the anxiety score on the Middlesex Hospital Questionnaire was present, but there was no correlation with other psychoneurotic traits or self-rating depression scores. Two to 3-year follow-up after management with a high fiber diet in 14 patients, showed that symptoms had improved greatly in seven, were unchanged in five, and were worse in two. Although dietary fiber had increased by a mean of 6.7 g/day, the clinical course could not be correlated with the amount of fiber consumed nor was it possible to predict the course of the individual patient from any clinical or psychological score. Despite persistence of symptoms at follow-up these were generally less severe and associated with significant decreases in anxiety, somatic and self-rating depression scores with the somatic score correlating with a decrease in clinical severity.