The newly developed XE-2100 haematology analyser can provide complete blood counts, leukocyte differentials, perform reticulocyte analysis, and obtain quantitative data on nucleated red blood cells (NRBCs). In this study, we evaluated the basic performance of this instrument using routinely obtained blood specimens treated with ethylenediaminetetraacetic acid-2K. Reproducibility, carryover, stability during storage at 4 degrees C and room temperature, and accuracy were evaluated. In this evaluation, reproducibility was good and little carryover was found. Accurate measurements were possible for up to 48 h of storage. A good correlation between findings with the XE-2100 and SE-9000 haematology analysers was found for complete blood count on 210 samples tested. The leukocyte differential obtained with the XE-2100 correlated well with eye counts and with the results obtained with the SE-9000 automated haematology analyser, with r values over 0.9 for the percentages of neutrophils, lymphocytes and eosinophils. The precision and accuracy of VRBC and reticulocyte counts by the XE-2100 were satisfactory. We used the XE-2100 to obtain differential counts for bone marrow aspirates, and good correlations with manual differentials were obtained for total nucleated cell count, percentage of myeloid cells and percentage of erythroid cells. The performance of the XE-2100 was excellent, and this instrument should be able to provide reliable data to clinical laboratories.