Employees at a health center in Georgia were concerned that symptoms experienced by some employees were related to pesticide exposure at the center. Malathion and DDT, used for mosquito control from 1969 to 1981, had been stored and handled at the center's first floor. We surveyed 117 (91%) of 129 employees to determine whether reported symptoms were associated with pesticide exposure. We performed environmental sampling for pesticides. We analyzed serum samples for 17 chlorinated pesticides, and urine samples for malathion. We found that 37% of the participants had reported a diagnosis of sinusitis and 24% of bronchitis since working at the health center. Frequently reported symptoms were eye irritation (44%) and headache (68%). DDT and malathion were found at levels of 2.4 and 11%, respectively, in bulk samples from the loading dock of the building. Multivariate analysis of responses to the questionnaire showed that the perception of odors, inadequate air flow, and length of employment were significantly associated with the employees' health complaints. Pesticide concentrations in employees' serum and urine samples were not associated with any health complaint. The health complaints reported by the employees at the health center were precipitated by both environmental and psychological factors. The epidemiology and laboratory components of this study highlight the importance of obtaining biological measurements in episodes of perceived environmental exposure.