Objective To investigate the clinical characteristics of postinfectious irritable bowel syndrome (PI-IBS) in Qingdao. Methods Two hundred and four PI-IBS and 2068 non-PI-IBS patients were investigated with questionnaire including general information, symptoms and quality of life scores with microecological study before and after therapy. Results (1) The morbidity rate of PI-IBS in female was 2. times of that in male, which was similar to that in non-PI-IBS. (2) Brainwork labors dominated in both PI-IBS and non-Pl-lBS patients. (3) As to the simultaneous presence of extra-gastrointestinal symptoms,there was no statistical difference between the rate of physical symptoms in PI-IBS and non-PI-IBS patients (X<'2>= 10. 5, P>0.05) ,but the rate of mental symptoms was higher in PI-IBS than in non-PI-IBS patients, and the difference was significant(X<'2>= 28.7, P<0.05). (4)The alteration of intestinal microflora rate in PI-IBS was obviously higher than that in non-PI-IBS patients. (5) The quality of life scores in PI-IBS was improved after treatment with Birid Triple Viable , and there was significant difference(t =3. 8, P<0.01),but there was no statistical difference in non-Pl-IBS (t = 1.5, P>0.05). Conclusion There was some difference in certain clinical characteristics between PI-IBS and non-PI-IBS patients in Qingdao.