OBJECTIVES: The purpose of this Italian multicenter study was to define pediatric upper reference values for urine particle quantification by using automated flow cytometry. DESIGN AND METHODS: Four hospital-based clinical laboratories participated in this multicenter investigation, which included a total study population of 161 Italian children aged from 1 to 12years. Two laboratories used Sysmex UF-100 and analyzed 86 children, whereas the other two used Sysmex UF-1000i and analyzed 75 subjects. Particle quantification included the analysis of white blood cells (WBC), red blood cells (RBC), squamous epithelial cells (EC), transitional epithelial cells (TC), casts (CAST) and bacteria (BACT). RESULTS: The upper reference values in subjects tested with the Sysmex UF-100 were 9.7WBC/μL, 10.1RBC/μL, 7.5EC/μL, 2.5TC/μL, 0.7CAST/μL and 3090BACT/μL, whereas the upper reference values in subjects tested with the Sysmex UF-1000i were 10.5WBC/μL, 8.3RBC/μL, 7.2EC/μL, 2.9TC/μL, 0.7CAST/μL and 48BACT/μL. No statistically significant differences between genders were found in the value distribution of any of the parameters tested. Similarly, no statistically significant differences were observed between the two urine analyzers, except for BACT. CONCLUSIONS: Automated analysis of urine particles appears a suitable means to optimize the workflow of routine urinalysis of children specimens. The upper reference limits for pediatric subjects obtained in this study were comparable to those previously reported in the literature, with no significant differences between genders and analyzers.