Adenovirus is a family of double stranded DNA viruses that are a significant cause of upper respiratory tract infections in children and adults. Less commonly, the adenovirus family can cause a variety of gastrointestinal, ophthalmologic, genitourinary, and neurologic diseases. Most adenovirus infections are self-limited in the immunocompetent host and are treated with supportive measures. Fatal infections can occur in immunocompromised patients and less frequently in the healthy. Adenoviral vectors are being studied for novel biomedical applications including gene therapy and immunization. In this review we will focus on the spectrum of adenoviral infections in humans.