On April 25, 2011, the Maine Center for Disease Control and Prevention was notified of a suspected case of hantavirus pulmonary syndrome (HPS) in a man aged 70 years with no recent out-of-state travel. The Maine resident went to a community hospital in early April with a 5-day history of fatigue, decreased appetite, weakness, chills, myalgias, and progressive shortness of breath. On examination, he was hypoxic and tachypneic. The patient was admitted with laboratory evidence of acute renal insufficiency, leukocytosis and thrombocytopenia, and appearance of diffuse bilateral infiltrates on chest radiograph. Two days later, he was transferred to a tertiary-care facility for management of respiratory failure with hypoxemia and worsening renal insufficiency. The next day, he was intubated and mechanically ventilated. Serum specimens demonstrated high titers of hantavirus reactive immunoglobulin M (1:6,400) and immunoglobulin G (1:1,600) antibodies. Hantavirus RNA was detected in the patient's blood. The patient was discharged to a skilled nursing facility 1 month after admission and is recovering with extensive rehabilitation.