An outbreak of illness in an electronics manufacturing facility in the Northeast United States was studied. Employee complaints of dizziness, odor, eye irritation, headache, and nausea recurred in April and May 1982. Representatives from OSHA and private firms performed extensive air sampling for carbon-monoxide (630080), methane (74828), hydrogen-sulfide (7783064), toluene (108883), trichloroethane (79005), ethyl-acetate (141786), Freon (11126059), and other halogenated hydrocarbons. Water supplies and ventilation systems were examined. A questionnaire designed for investigating psychogenic illness was completed by 97 percent of the work force. Blood gas analysis was performed on seven ill workers. No physical or chemical basis for the illness could be determined. Air samples showed no potentially hazardous concentrations and ventilation was judged adequate. Ill employees were most often female. Respondents to the questionnaire were often not able to establish the onset of the illness and no apparent pattern of attack rates could be defined. Blood gas analysis of ill workers showed respiratory alkalosis consistent with hyperventilation. The authors conclude that the poorly defined nature of the disease and the absence of hazardous substances, with the confirmation of hyperventilation, suggest an episode of psychogenic illness.