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OBJECTIVES This study examined the impact of various preanalytical variables on metaphase yield in hematologic malignancies. METHODS Marrow samples from patients with hematologic malignancies that were subjected to cytogenetic analysis were categorized into two groups: one with samples that yielded an adequate number of metaphases, defined as at least 20, and a second with a low number of metaphases (LNM), having fewer than 20 metaphases. Age, sex, bone marrow nucleated cell (MNC) count, and peripheral blood counts (hemoglobin, total WBC count, and platelet count) were analyzed for an association with LNM. RESULTS Of 455 samples, 17% (79/455) belonged to the LNM group, including 6% (27/455) that yielded no metaphases. MNCs and WBCs were higher in the LNM group (P < .001 for both). MNCs were higher in LNM groups in both acute myeloid leukemia (P = .008) and acute lymphoblastic leukemia (P = .001). Receiver operating characteristic curves showed moderate prediction of MNC and WBC counts for LNM with areas under the curves of 0.7. Other analyzed parameters showed no significant associations with LNM. CONCLUSIONS Low metaphase yields occur frequently in hematologic malignancies with high counts. This could reflect biological characteristics of these malignancies that merit further investigation.