Cellular analysis of body fluids, including cerebrospinal fluid and serous fluids, provides essential information in the differential diagnosis. Improper techniques and inaccurate results may lead to the under or over-diagnosis of disorders such as meningitis and peritonitis. In most laboratories, white blood cells are counted using manual microscopy; however, this technique has a high imprecision and wide inter-observer variability. In view of these limitations, automated analyzers, initially developed for whole blood and urine samples, have become popular for first line screening. In this thesis, we evaluated several automated analyzers equipped with a special body fluid mode in a variety of diagnostic body fluids, and reported on the result.