Associations between the office environment and health conditions were investigated in this NIOSH study. Eighty office buildings were examined in 1993. Health questionnaires, concerning symptoms present only during the work day, were administered to workers. In order for workers to be identified with multiple lower respiratory symptoms, at least three of the following symptoms were required: shortness of breath, cough, chest tightness, and wheezing. In order for workers to be identified with multiple atopic symptoms, sneezing, eye irritation, and a runny nose or nasal congestion were required. Work related cases of diagnosed asthma were also considered. A mean prevalence of about 2.5% was determined for both asthma and respiratory symptoms, while a prevalence of 7.6% was calculated for atopic symptoms. Lower respiratory symptoms were related to the cleanliness and efficiency of the heating, ventilation, and air conditioning (HVAC) systems. The highest relative risk (RR) of lower respiratory symptoms, 3.1, was determined for debris present inside the air intake of the HVAC system. Atopy was significantly associated with the testing and cleanliness of the HVAC system, as well as ceiling panels, surface dusting, and pesticides. The highest RR of atopy, 2.3, was observed for the presence of ceiling panels. Asthma was related to the cleanliness of the HVAC system and the use of cloth partitions. The highest RR of asthma, 2.5, was determined for recent renovations involving new dry wall. In models adjusted for age and gender, the highest RR, 2.9, was determined for asthma among females. Occupational conflicts were related to all three health problems. The authors conclude that this analysis serves to recognize office building conditions which may be related to the development of ill health among workers. The results indicate the importance of following HVAC system guidelines.