Objective: To determine the efficacy and tolerability of phloroglucinol, an antispasmodic agent in the treatment of Irritable Bowel Syndrome (IBS). Methods: It was an open label (quasi interventional) study. One hundred patients coming to the gastroenterology clinics of Aga Khan University Hospital with IBS as defined by the Rome II criteria were enrolled between February 2004 and September 2004 to participate in the trial and were treated as outpatients. Phloroglucinol (Himont) 50mg orally three times daily was given for two months. Symptoms were assessed before and during treatment using a questionnaire. Results: One hundred patients were enrolled in the study. Of them 61% (61/100) were males and 39% (39/100) were females. Their mean age was 41±14 years. Sixty-eight patients completed the study and 28 dropped out. On Phloroglucinol treatment there was an overall statistically significant improvement in abdominal pain (p<0.001), frequency of stools per day (p<0.001), urgency (p<0.001), passage of mucus per rectum (p<0.001),sense of incomplete defecation (p=0.001) and bloating (p=0.001). However, no response was seen in the feature of straining in both genders (p=0.676). The difference in response to treatment according to gender separately showed statistically significant improvement in the sense of incomplete defecation in females alone(p=0.003). Conclusion: Phloroglucinol in a dose of 50mg three times daily is effective and well tolerated by the IBS patients. It relieves most of the symptoms of IBS (JPMA 56:5;2006)