We evaluated performance of the ABX PENTRA 80 (ABX Diagnostics, Montpellier, France) hematology analyzer in enumerating the most frequent subsets of WBCs in peripheral blood, atypical lymphocytes (ALYs), and large immature cells (LICs) by comparing results with those obtained by manual microscopic counts, another hematology analyzer, and flow cytometric immunophenotyping. Identification and enumeration of neutrophils and lymphocytes with the PENTRA 80 showed high correlation with all 3 reference methods (R2 > or = 0.92 and R2 > or = 0.88, respectively); quantification of eosinophils showed good correlation with the other analyzer and flow cytometric immunophenotyping (R2 > or = 0.70); lower correlation coefficients were found for comparisons with conventional microscopy (R2 > or = 0.50). For monocytes, lower but acceptable correlation and agreement were found; marginal correlation was found for basophils. The PENTRA 80 also showed good performance in detecting LICs but was less effective for the identification of ALYs in relatively low frequencies in abnormal peripheral blood samples. We found good performance of the 5-part leukocyte differential analyses for the PENTRA 80, especially for enumeration of neutrophils, lymphocytes, eosinophils, and LICs.