Febrile illnesses of infective aetiology are common causes of hospital admission in tropical countries. In Sri Lanka, the incidence of dengue infection has markedly increased during the last 15 years whilst infections such as leptospirosis and viral hepatitis A remain endemic. Most of the common infections share a common and non-specific symptomatology, making diagnosis at initial presentation difficult. Similarly co-infections can complicate the clinical course but may remain undetected unless a high index of suspicion is maintained especially during epidemics of one infection. We report two cases of co-infections, highlighting the importance of this possibility. Coexistence of dengue infection with hepatitis A in one patient and with leptospirosis in another patient resulted in an atypical and protracted course of illness with confusing clinical features in either case.