Diagnosis of Dengue Hemorrhagic Fever (DHF) is based on clinical and supporting examinations, including leukocytes and platelets examinations and antigen and antibody tests for the dengue virus. Examining leucocytes, thrombocytes, and immature platelets is a routine protocol in DHF patients. Leucocytes, thrombocytes, and immature platelets in dengue hemorrhagic fever have their characteristics and roles in relation to the disease severity. Prompt and early diagnosis will reduce the risk of disease severity. This review described the characteristics and role of leucocytes, thrombocytes, and immature platelets in dengue hemorrhagic fever.