A b s t r a c tWe evaluated the Sysmex UF-100 urine flow cytometer (TOA Medical Electronics, Kobe, Japan) The development of automated blood cell analyzers has prompted several attempts to produce similar devices for urinalysis. The first commercially available instruments were the Yellow IRIS (International Remote Imaging Systems, Chatsworth, CA) in the United States' and the Sysmex UA series (TOA Medical Electronics, Kobe, Japan) in Japan. 2Demands for a higher level of automation and satisfactory differentiation of specific urine particles have been the driving forces for improvement.We evaluated a second-generation urine flow cytometer, the Sysmex UF-100 (TOA Medical Electronics) by comparing its performance with chamber counting of Sternheimerstained noncentrifuged specimens and with conventional bacterial cultures on cystine-lactose-electrolyte-deficient (CLED) agar plates. Routine reflectometric test strip measurements and morphologic analyses based on the Finnish recommendations 3 were also performed for comparison. The characterization of formed elements with the UF-100 analyzer is based on flow cytometry of particles doublestained for DNA and membranes; particle identification involves measurement of forward-scattered light intensity and fluorescent light intensity, and the widths of these signals. Conductivity of the sample is measured before it enters the flow cell to adjust a constant electrical current in the flow cell for the impedance measurement. The final differentiation is accomplished with multiparametric algorithms (adaptive cluster analysis). A quantitative report is given for RBCs, WBCs, (large) epithelial cells, bacteria, and casts. Additional information flags are provided to indicate the presence of inclusional casts (granular or cellular casts),