Complaints of office employees working in a closed building were studied. After employee complaints of odors and illnesses attributed to working in the building, physical examinations and blood and urine tests proved unremarkable. The heating, cooling, and ventilation of the office building with sealed windows were examined. Symptoms were studied through a questionnaire answered by 248 employees. Working conditions were evaluated with regard to the number of workers in the immediate environment, the number of smokers, and the frequency and type of photocopier use. Laboratory tests were made for a number of common contaminants including formaldehyde (50000) and carbon-monoxide (630080), and the soiling index was calculated as a measure of suspended particulates. Engineering studies showed that total fresh air entering the building was about 6 cubic feet a minute (cfm) per worker. Symptoms of memory loss, confusion, drowsiness, dizziness, giddiness, eye problems, headache, nausea, nose irritation, and increased urinary frequency were reported, with most symptoms among young females and workers working using photocopiers with wet processing. Laboratory tests indicated 0.04 to 0.08 parts per million formaldehyde. Other contaminants were not found in concentrations sufficient to cause problems. Soiling index did indicate excessive particulate matter in the air. Increasing fresh air to 20cfm per worker caused decreased soiling index. Symptoms improved. The authors conclude that complaints due to closed buildings are increasingly common. Consideration must be given to increasing the ventilation rate to about 35cfm.