Adenoviruses are a family of DNA viruses that are an important cause of febrile illnesses in young children. They are most frequently associated with upper respiratory tract syndromes such as pharyngitis but can also cause pneumonia and less commonly, gastrointestinal, ophthalmologic, genitourinary, neurologic, and disseminated disease. Most adenoviral diseases are self-limiting, although fatal infections can occur in immunocompromised patients and occasionally in healthy children and adults.