Background: Dengue is a widespread disease affecting many countries and about two fth of the world is at risk for this disease. In India, the dengue incidence has increased in recent past and emerged as an important health problem in many states including Odisha. Cases with dengue co-infection with other diseases usually have atypical clinical presentation. Methods: A facility based longitudinal study was carried out over a period of one year to determine the dengue co-infection and its outcome. The suspected cases were clinically assessed following a standard case report format and serological investigations including serotyping were carried out.Results: 33.6% samples were dengue positive of which 78.5% were positive for NS1 Ag, 26.6% positive for dengue IgM and 5.1% to both. Among the dengue positive cases, 60.9% were male and mean age was 31.52 (+/-17.03) years. High occurrence of cases was during May to November with maximum in August. Among the 975 dengue positives, 57 (5.8%) were found to have co-infection. Chikungunya was the most common co-infection in 71.9%, followed by herpes simplex (HSV) (7%) and other diseases.Fever was the most common presenting symptom (98.2%), followed by myalgia (91.2%), pain abdomen (12.3%), Rash/lesion (8.8%), burning micturition (5.3%), Petechiae (1.7%) and Pruritus (1.7%) among the co-infected cases.While DEN-2 serotype was observed in majority (74.1%) more than two serotypes was found in 5.85% of dengue positives .Conclusions: All the four dengue serotypes were found to be circulating with DEN-2 as the most predominant one. About 5.8% of dengue cases have co-infection (mainly with chikungunya) and clinically present with atypical signs and symptoms.