Adenovirus infections in 201 bone marrow transplant (BMT) recipients over 4 years were retrospectively reviewed. Forty-two patients (20.9%) had positive adenovirus cultures after BMT. There was a higher incidence of adenovirus infections in pediatric patients than in adults (31.3% vs. 13.6%, P = .003). In addition, the time of onset of adenovirus infection after transplant was earlier in pediatric patients (mean, < 30 days) than in adults (> 90 days). Adenovirus type 35 was the most common serotype identified. One-third of adenovirus-positive patients had definite or probable adenovirus disease. Moderate to severe acute graft-versus-host disease and isolation of adenovirus from two or more sites were significant risk factors for adenovirus disease. This report documents a higher incidence of both adenovirus infection and disease than do previous studies. Adenovirus may emerge as a more frequent pathogen as more high-risk BMT transplants are done.