Background: Moxibustion is increasingly used for treatment of irritable bowel syndrome (IBS). This study investigated the long-term effects of moxibustion for IBS with diarrhea (IBS-D). Methods: Patients with IBS-D were assigned to receive moxibustion or sham moxibustion (52 each, 3× per week, 6 weeks) and were followed up to 24 weeks. The acupoints were bilateral ST25 and ST36, body surface temperatures at acupoints were 43°C ± 1°C and 37°C ± 1°C for the moxibustion and sham groups, respectively. Primary outcome was changes in IBS Adequate Relief (IBS-AR) from baseline to 6 weeks. Secondary outcomes included the following: IBS symptom severity scale (IBS-SSS), Bristol stool form scale (BSS), IBS quality of life (IBS-QOL), and Hospital Anxiety and Depression Scale (HADS). Results: Based on an intention-to-treat analysis, the rate of IBS-AR in the moxibustion group was significantly higher than the sham group at 6 weeks (76.9% versus 42.3%; p 50 points in IBS-SSS of the treatment group was significantly higher than that of the sham ( p