BackgroundReference intervals are critical for interpreting test results of a clinical laboratory. The aim of this study was to establish local reference intervals of complete blood count for healthy preschoolers in China. MethodsThree thousand eight hundred and twenty-one blood specimens from children aged 4months to 6years were collected and analyzed. Complete blood counts were determined by Sysmex XT-4000i Automated Hematology Analyzer. The nonparametric 2.5th to 97.5th percentile reference ranges were calculated according to CLSI EP28-A3c guideline. ResultsReference intervals for each blood cell parameter are determinded as follows: total WBC 4.86-12.1x10(9)/L for males and 4.73-12.3x10(9)/L for females; RBC 4.13-5.32x10(12)/L for males and 4.08-5.24x10(12)/L for females; HGB 109-145g/L for males and 111-143g/L for females; HCT 33.1-41.2% for males and 33.3-41.1% for females; MCH 23.5-29.7pg for males and 24.6-30.0pg for females; MCHC 320-365g/L for males and 321-362g/L for females; MCV 71.4-85.1fL for males and 73.8-86.9fL for females; RDW-SD 33.5-41.9fL for males and 33.5-41.0fL for females; RDW-CV 12.0-15.2% for males and 11.8-14.5% for females; PLT 181-475x10(9)/L for males and 179-456x10(9)/L for females; PCT 0.18-0.44% for males and 0.18-0.43% for females; MPV 8.20-11.6fL for males and 8.20-11.5fL for females; PDW 8.40-14.4fL for males and 8.40-14.0fL for females; P-LCR 12.0-36.6% for males and 11.8-35.6% for females. ConclusionsWe established local complete blood count reference intervals for apparent healthy preschoolers in China. It is necessary to establishing region-specific reference intervals of complete blood count for preschoolers.