AIM：To explore the value of fecal lactoferrin in predicting and monitoring the clinical severity of infectious diarrhea.METHODS：Patients with acute infectious diarrhea ranging from 3 mo to 10 years in age were enrolled,and one to three stool samples from each subject were collected.Certain parameters,including white blood cells /differential count,C-reactive protein,fecal mucus,fecal pus cells,duration of fever,vomiting,diarrhea and severity（indicated by Clark and Vesikari scores）,were recorded and analyzed.Fecal lactoferrin was determined by enzyme-linked immunosorbent assay and compared in different pathogen and disease activity.Generalized estimating equations（GEE） were also used for analysis.RESULTS：Data included 226 evaluations for 117 individuals across three different time points.Fecal lactoferrin was higher in patients with Salmonella（11.17 μg/g ± 2.73 μg/g） or Campylobacter（10.32 μg/g ± 2.94 μg/g） infections and lower in patients with rotavirus（2.82 μg/g ± 1.27 μg/g） or norovirus（3.16 μg/g ± 1.18 μg/g） infections.Concentrations of fecal lactoferrin were significantly elevated in patients with severe（11.32 μg/g ± 3.29 μg/g） or moderate（3.77 μg/g ± 2.08 μg/g） disease activity compared with subjects with mild（1.51 μg/g ± 1.36 μg/g） disease activity（P 〈 0.05）.GEE analysis suggests that this marker could be used to monitor the severity and course of gastrointestinal infections and may provide information for disease management.CONCLUSION：Fecal lactoferrin increased during bacterial infection and with greater disease severity and may be a good marker for predicting and monitoring intestinal inflammation in children with infectious diarrhea.