The aim of this study was to analyze the usefulness of fecal lactoferrin in the diagnosis and monitoring of inflammatory bowel disease (IBD) in children. The study included 52 children with IBD (24 with Crohn's disease and 28 with ulcerative colitis) aged between 0.92 and 18 years, and 41 IBD-free controls of similar age. Fecal concentration of lactoferrin was determined with a quantitative immunoenzymatic test. Fecal concentration of lactoferrin in children with IBD was significantly higher than in the controls. The cut-off value of fecal lactoferrin concentration optimally distinguishing between the children with IBD and the controls was identified as 13 μg/g. The sensitivity and specificity of this cut-off value equaled 80.7% and 92.7%, respectively, and its positive and negative prognostic values were 96.8% and 63.3%, respectively. Patients diagnosed with moderate Crohn's disease had significantly higher fecal concentrations of lactoferrin than children with the mild or inactive disease. Similarly, children with moderate ulcerative colitis showed significantly higher fecal concentrations of lactoferrin than individuals with the mild condition. No significant relationship was found between the fecal concentration of lactoferrin and the severity of endoscopic lesions. Patients with IBD and a positive result of fecal occult blood test were characterized by significantly higher concentrations of lactoferrin than the individuals with IBD and a negative result of this test. In conclusion, fecal concentration of lactoferrin seems to be a useful parameter for diagnosis and monitoring of IBD in children.