The enumeration and identification of blood cells in body fluids offers important information for the diagnosis and treatment of various medical conditions. Manual microscopic methods (hemacytometer total cell count and cytocentrifuged differential count) have inherent analytic and economic disadvantages but are still considered the "gold standard" methods. We evaluated the analytic and clinical performance of the Cell-Dyn Sapphire hematology analyzer (Abbott Diagnostics Division, Santa Clara, CA) for automated blood cell counting and leukocyte differential counting in cerebrospinal fluid, serous fluid (peritoneal and pleural fluid), and continuous ambulatory peritoneal dialysis fluid, and we compared the performance with the respective manual methods. In the present article, we describe its applicability for the distinct body fluids, and we highlight limitations and caveats.