Little is known about the prevalence and clinical course of dengue infection in elderly patients living in endemic areas; it is presumed that there is a lower prevalence but higher severity, complications and mortality. To describe the prevalence and clinical course of dengue infection in elderly patients who were admitted to a referral care center for infectious diseases in an endemic region. We conducted an observational and descriptive study between 2011 and 2014, using a cohort of elderly patients with serological diagnosis of dengue. A total of 235 febrile elderly patients were assessed, of which 43 patients (18.3%) were found to have dengue. The median age was 71 years; 48.7% were female, and 89% of patients had at least one comorbid condition. According to the serological tests, 51.4% of cases were positive for NS1 Ag, 27% for IgM and 54.1% for IgG, while 64.8% were secondary infections. Dengue was diagnosed in 13 patients (35%), dengue with warning signs in 16 cases (43%), and severe dengue in 8 cases (22%). Nearly 56.7% of patients were admitted to hospital and 21.6%, to the intensive care unit. None died. We found dengue infection to be more frequent than expected in this sample of elderly patients, due to acute febrile syndrome. Elderly patients also required higher rate of hospitalization and had more complications, however there were no deaths due to good management.