Overuse of antibiotics for the treatment of acute diarrhea is very common. The aim of the current study was to investigate the inappropriate use of antibiotics in adults with acute infectious diarrhea and to evaluate the association between the use of antibiotics and clinical features. To achieve this aim, we reviewed 4891 patients' medical records from Apr. 2008 to Oct. 2009. Of the total 4891 cases, 30.5% had clinical features of invasive bacterial diarrhea, 48.1% were prescribed with antibiotics, and 20.3% received inappropriate antibiotic treatment. Of note, 19% involved unnecessary antibiotic prescriptions in non-indicated cases, which accounted for 39.4% of all antibiotics prescribed in the total 4891 patients. There was no significant differences between physicians and medical trainees in the inappropriate use of antibiotics (P = 1.0). Logistic regression analysis demonstrated that except for body temperature, other clinical symptoms including abdominal pain, tenesmus, and faecal WBC count (〉10 cells/HPF) were associated with the use of antibiotics. In addition, other clinical indicators including vomiting, stool frequency of 5-10 times/d, mucous stool, and fecal WBC count of 1-10 cells/HPF, which are not normally indicators for prescribing antibiotics, were also associated with the use of antibiotics. This might suggest that these symptoms were mistaken as features of invasive bacterial diarrhea, thus leading to the overuse of antibiotics.