ISEE-0400 Background and Objective: Poor hospital environmental quality may result in sick-building syndromes (SBS) among healthcare workers and patients. In 2007, we conducted a prospective study to evaluate the health effects of indoor environmental quality among healthcare workers in Taiwan. Methods: We used air capture hood (Model 8373, TSI AccuBalance Plus) to evaluate the air change per hour for each unit. A self-reported questionnaire was used to assess the demographic data, environmental/occupational exposures, and SBS. SBS was classified into 5 sub-groups: eyes mucous membrane, upper-, lower respiratory track, skin, and neuropsychology status. In addition, skin prick tests (Multi-Test® II, Lincoln Diagnostics) for 14 allergens and lung function tests (Micro Loop of Micro Medical Limited) were used to assess the respiratory effects. Multiple linear- and logistic regression were applied to assess the association of interest, respectively; as well to adjust the potential confounders. Results: 83.28% (513/616) of the workers agreed to participate in this study. The SBS prevalence's of eyes mucous membrane, upper-, lower respiratory track, skin, and neuropsychology status were 49.28%, 27%, 14.83%, 10.86% and 46.72%, respectively. 43.8% of the 152 workers were allergic to dust mites. The average FEV1 and PEF of the 189 lung function participants were 2.42 ± 0.5 ml and 361.97 ± 75.31 ml, respectively. After the adjustment for confounders, we found that “low air volume”, “temperature too hot and moist”, “uncomfortable chair”, “air cleaners”, “passive cigarette smoking”, “overloading job” and “allergy to dust mites” were the risk factors of SBS. Workers who had been exposed to patients’ blood, saliva or excrement in the workplace had higher risk of developing allergy, which may result in poor lung function. Conclusion: To protect the healthcare workers, we suggest offering comfortable environments and re-evaluating the ventilation facility.