This document provides information on white blood cell disorders, including qualitative and quantitative disorders. It discusses Chediak-Higashi syndrome, a rare autosomal recessive disorder characterized by abnormal granules in neutrophils resulting in decreased immune function. Leukemia is summarized as a malignant disorder of stem cells associated with increased white cells in bone marrow and blood. The classification, clinical features, investigations and management of acute leukemia are outlined.