Multiparameter flowcytometry (MFC) has become an integral tool for the diagnosis and classification of diseases. The most common application of flow cytometry is immunophenotyping of normal or abnormal cells. In addition, study of DNA content, apoptosis, cell cycle analysis, reticulocyte content, red cell fragility, neutrophilic oxidative burst analysis, red cell G-6 PD deficiency etc. are some other uses. Immunophenotyping is primarily required for the diagnosis and classification of haematological neoplasm. These are also used to detect the presence of metastasis from epithelial and haematological malignancy. Additionally, they are also an indispensable tool for the disease monitoring of different haematological neoplasm. Several laboratories also utilise the power of this diagnostic tool for the diagnosis of non-neoplastic haematological disorders. This includes disorder like paroxysmal nocturnal haemoglobinuria (PNH), hereditary spherocytosis, inherited platelet disorders, chronic granulomatous disease, leukocyte adhesion defects, hemophagocytic lymphohistiocytosis, primary lymphocytic immunodeficiency disorder etc. This chapter will provide brief information on the various clinical applications of flow cytometry that are used in a day-to-day practice.