Indian Subcontinent has emerged as a scene for mosquito–borne infectious diseases like Dengue fever. Maximum transmission and disease incidence is seen during the months of rainfall. This study aim to determine the seasonal variation of dengue infection. The present study was conducted retrospectively for a period of 1 year in JLN Medical College, Ajmer. All patients with clinical features and serologically positive dengue infections were included. Blood samples were collected from 473 patients suffering from febrile illness. Serological confirmation of Dengue Infection was done by NS1, IgM and IgG (Rapid strip test) which was serologically confirmed by the IgM ELISA. Out of 473 suspected cases, 194 cases (41 %) were confirmed as serologically positive. Maximum cases were seen during monsoon and post monsoon period. Rain, temperature and relative humidity as the important climatic factors, which could be responsible for Dengue infection