Dengue fever is a mosquito-borne tropical disease caused by the dengue virus. Symptoms typically begin three to fourteen days after infection. This may include a high fever, headache, vomiting, muscle and joint pains, and a characteristic skin rash. Recovery generally takes two to seven days. The present study was conducted in Department of Medicine, Adichunchanagiri Institute of Medical Sciences, from the period of January 2017 to December 2018 to Study of Clinical and Haematological profile of patients with dengue fever. In our study, the incidence of dengue fever common in males compared to females. Majority of patients were in the age group 31-40 years. Out of 100 patients 69(69%) patients were diagnosed to have DF, 24(24%) patients were diagnosed to have DHF and 7(7%) patients were diagnosed to have DSS based on WHO criteria. Fever was present in100 cases, myalgia in 94 cases, headache was present in 81 cases, joint pains in 90cases, vomiting in 74 cases, pain abdomen in 69 cases, rash in 52 cases, hepatomegaly in 21 cases, bleeding in 34 cases and shock in9 cases. As per WHO criteria 71(71%) patients had low platelet counts. Apart from attempts to control the spread of the Aedes mosquito there are ongoing efforts to develop antiviral drugs that would be used to treat attacks of dengue fever and prevent severe complications. Discovery of the structure of the viral proteins may aid the development of effective drugs