Several human adenoviruses (HAdVs) can cause respiratory infections, some severe. HAdV-B7, which can cause severe respiratory disease, has not been recently reported in the United States but is reemerging in Asia. During October 2013-July 2014, Oregon health authorities identified 198 persons with respiratory symptoms and an HAdV-positive respiratory tract specimen. Among 136 (69%) hospitalized persons, 31% were admitted to the intensive care unit and 18% required mechanical ventilation; 5 patients died. Molecular typing of 109 specimens showed that most (59%) were HAdV-B7, followed by HAdVs-C1, -C2, -C5 (26%); HAdVs-B3, -B21 (15%); and HAdV-E4 (1%). Molecular analysis of 7 HAdV-B7 isolates identified the virus as genome type d, a strain previously identified only among strains circulating in Asia. Patients with HAdV-B7 were significantly more likely than those without HAdV-B7 to be adults and to have longer hospital stays. HAdV-B7 might be reemerging in the United States, and clinicians should consider HAdV in persons with severe respiratory infection.