The effects of loperamide in patients with IBS (all had diarrhoea as a main symptom) were studied in a double-blind placebo controlled trial. Subjective overall response stool consistency and six individual symptoms (urgency, pain, frequency, flatulence, borborygmi and painful propulsions) were studied over a 13 week long treatment period. Twenty-one patients out of 25 completed the trial, 11 in the loperamide group and 10 in the placebo group. A significant advantage for loperamide was found for stool consistency (p less than 0.001), pain (p less than 0.02) and urgency (p less than 0.05). Subjective overall response was also significantly better in the loperamide group (p less than 0.03). Self-titration of dose and administration in a single nightly dose was safe and efficient.