Objective To investigate the epidemiologic features of an outbreak of SARS that occurred in a single diabetes room of a general hospital in Beijing in late March 2003.Methods Field investigation was carried out in the ward,the nursing log and the hospitalization medical record of correlative patients were consulted.SARS-CoV in serum specimen from SARS patient was detected by PCR.Results The room where SARS outbreak occurred was on the 13th floor of the 16-story main ward building.There were 6 beds in the room,living with 6 female patients(aged 45-67)who were all hospitalized due to type2 diabetes.On March 24,2003,Patient 1 began to have a fever and cough,chest X-ray showed pneumonia.Five and six days later,Patient 2 and Patient 3 began to have a fever,respectively.Finally,all of these 3 patients died.Their beds were all at the same side of the room,and the other 3 patients at the opposite side were not infected.Serum SARS CoV-RNA of the Patient 3 was positive by nest-PCR.The daughter-in-law of Patient 1who accompanied Patient 1 by the bedside several days,mainly near the window,upwind of Patient 1,was not infected.Medical staff,family members and visitors of the 6 patients were not infected.Conclusions This outbreak was not transmitted by aerosol.The distance droplets travels could be up to 3.43 meters.Droplet spread has direction,and the droplets direction of propagation is closely related with the wind direction and speed.Those at the downwind position of SARS patients were susceptible to be infected.Medical staff wore face masks and good natural ventilation of this ward building may be important reasons for the prevention of infection. Objective To investigate the epidemiologic features of an outbreak of SARS that occurred in a single diabetes room of a general hospital in Beijing in March March. Methods Field investigation was carried out in the ward, the nursing log and the hospitalization medical record of correlative patients were consulted.SARS-CoV in serum specimen from SARS patient was detected by PCR.Results The room where SARS outbreak occurred was on the 13th floor of the 16-story main ward building.There were 6 beds in the room, living with 6 female Patients (aged 45-67) who were all hospitalized due to type 2 diabetes. On March 24, 2003, Patient 1 began to have a fever and cough, chest X-ray showed pneumonia. Five and six days later, Patient 2 and Patient 3 began to have a fever, respectively. All of these 3 patients died. The beds were all at the same side of the room, and the other 3 patients at the opposite side were not infected. Serum SARS CoV-RNA of the Patient 3 was positive by nest-PCR.The daughter-i n-law of Patient 1who accompanied Patient 1 by the bedside several days, mainly near the window, upwind of Patient 1, was not infected. Medical staff, family members and visitors of the 6 patients were not infected. by aerosol. The distance droplets travels could be up to 3.43 meters. Droplet spread has direction, and the droplets direction of propagation is closely related with the wind direction and speed.Those at the downwind position of SARS patients were susceptible to be infected. Medical staff wore face masks and good natural ventilation of this ward building may be important reasons for the prevention of infection.