question: Human coronaviruses (HCoVs) cause upper respiratory tract and occasionally lower respiratory tract diseases. The recently described human coronavirus NL63 has not been well investigated among Brazilian patients. We reported the clinical course of an HCoV-NL63 infection in a hospitalised patient suspected of H1N1 2009 infection during the second pandemic wave of influenza activity. A 46-year-old female, health care worker with diabetes and presenting with influenza-like illness (ILI) was admitted to the hospital. During 9 days of influenza-like symptoms, the patient had diabetes decompensation, haemorrhagic pneumonia, rhabdomyolysis, respiratory and renal failure, pericarditis, and brain edema and died. HCoV-NL63 may be a causative agent of previously unexplained respiratory illnesses.