Flow cytometry has rapidly evolved into a technique for rapid analysis of DNA content, cellular marker expression and electronic sorting of cells of interest for further investigations. Flow cytometers are being extensively used for monitoring of cellular DNA content, phenotype expression, drug transport, calcium flux, proliferation and apoptosis. Phenotypic analysis of marker expression in leukemic cells has become an important tool for diagnostic and therapeutic monitoring of patients. Recent studies have explored the use of flow cytometry for monitoring hormone receptor expression in human solid tumours and for studies in human genomics. Contributions in the current volume are based on presentations made at the First Indo-US workshop on Flow Cytometry in which experts from USA, UK and India discussed applications of flow cytometry in biological and medical research. This book should be of interest to post graduates and researchers in the fields of pathology, cytology, cell biology and molecular biology.