OBJECTIVE:To investigate the effects of warming moxibustion Tianshu (ST 25,bilateral) and Qihai (CV 6) in patients with diarrhea-dominant irritable bowel syndrome (D-IBS) by assessing predominant factors,and determining the best factor combinations and their interactions.To identify the optimal quantity of warming moxibustion Tianshu (ST 25,bilateral) and Qihai (CV 6) to achieve optimal efficacy.METHODS:An L9 (34) orthogonal design was applied to 233 confirmed subjects based on the three most influential factors and the three most frequently used levels.Nine programs were designed.Subjects were assigned to four subgroups according to age and gender;each subject underwent one of the nine programs randomly.We selected Tianshu (ST 25,bilateral) and Qihai (CV 6).The scores of symptoms and the IBS Quality of Life (IBS-QOL) were evaluated after the final treatment.RESULTS:After treatment,clinical symptoms of all patients were significantly improved (P =0.001).Quality of life also improved significantly (P ＜ 0.05).For all the participants,frequency was the dominat ing factor regarding symptoms (P =0.01).Duration was the dominating factor for quality of life (P =0.0001).The best combination for improving symp toms in 30-40-year-old male and female patients was two courses of 10 min each once a day,and for 41-50-year-old male and female patients it was three courses of 10 min (males) or 30 min (females) twice a day.The best combination for quality of life was three courses of 20 min once a day.No interaction was found between frequency and course,or frequency and duration.CONCLUSlON;Warming moxibustion Tianshu (ST 25,bilateral) and Qihai (CV 6) is a promising therapy for D-IBS.To acquire optimal efficacy,the three main factors (duration,frequency and treatment course) of the warming moxibustion should reach a specific quantity and be combined appropriately.