This study aims to investigate the characteristics of indoor air quality (IAQ) in hospital from August to October, 2005. The field measurement was conducted in 20 hospitals located in Seoul and Kyonggi province. The collected samples are PM10, PM2.5, formaldehyde, total bacteria counts(TBC), CO 2, CO, NO2, O3, radon, asbestos, total volatile organic compounds(TVOCs) in indoor air and evaluated by the IAQ standard operating method of Ministry of Environment in Korea. In particle matter (PM10) showed the range from 10.600 μg/m2 to 180.900 μg/m2 The average concentration was 60.135 μg/m2 and showed less than that of Korea IAQ standards. And the indoor air pollutants exceeded the air quality standard of Ministry of Environment in Korea(MEK) was TVOCs, asbestos, PM2.5, O3 and showed the percentage of 20%, 18.4%, 12.5%, and 7.5% respectively.