Background: Dengue is the most rapidly spreading mosquito borne viral disease in the world. There is an increase in incidence of dengue in adult population in South Asian countries in recent years. Objective: To study the pattern of dengue in adults and the significance of total leukocyte count in assessing the clinical course of dengue. Materials & Methods: All adult patients admitted with fever and features suggestive of dengue infection were included in the study. Serological testing for dengue virus specific antigen and antibody was done for the diagnosis of dengue fever. The demographic data, clinical features, hematological and biochemical parameters were collected. The World Health Organization classification and case definitions 2009 was used to categorize the dengue patients. The variable pattern of the disease and the importance of total leukocyte count in the monitoring of the natural course of the illness were studied. Results: Of the total 169 patients admitted with suspected dengue infection, 74 were diagnosed with dengue serologically. Of these 74 patients, 31(41.9%) had primary dengue infection and 43 (58.1%) had secondary dengue infection. Number of patients who had probable dengue, dengue +warning signs and severe dengue were 39 (52.7%), 24 (32.4%) and 11 (14.9%) respectively. Petechiae were seen in 22 (29.7%) patients, tender hepatomegaly in 18 (24.3%). A very low total leukocyte count and a very low