Indicaiton of Hemoglobin (Hb) estimation, Total and differential count (TC, DC) their normal range, physiological and pathological variation, steps of hemoglobin estimation by different commonly used techniques, preparation and staining of a peripheral blood film (PBF), interpretation of a PBF are clearly and meticulously described. Also causes of leukocytosis, leucopenia, neutrophilia and neutropenia, lymphocytosis and lymphopenia, monocytosis, basophilia and basopenia, eosinophilia and eosinopenia are discussed.