Irritable bowel syndrome (IBS) is a chronic condition for which there is no consensus on the optimum treatment. Gastroenterology problems are some of the most common conditions treated by homeopaths, yet few trials have explored the effectiveness of individualised homeopathic treatment for IBS. A three-armed trial was conducted which compared: usual care, homeopathic treatment plus usual care and supportive listening plus usual care. The primary outcome was change in irritable bowel symptom severity score between baseline and 26 weeks, calculated using ANCOVA. An interim ANCOVA adjusted for baseline IBS severity, age and employment status found no statistically significant difference between the three arms. However, a post-hoc test comparing homeopathic treatment plus usual care to usual care alone found a statistically significant difference in favour of homeopathic treatment. In addition, 62.5 percent of patients in the homeopathic treatment arm (compared to 25.0 percent of those in the usual care arm), achieved a clinically relevant change in irritable bowel symptom severity score, which indicates a promising effect for homeopathic treatment, though these results should be interpreted with caution due to the low number of participants in the study.