An outbreak of metal fume fever (MFF) among workers involved In cutting brass pipes with electric cutting torches in an enclosed, poorly ventilated steam condenser is described. Twenty-six workers were affected. Symptoms most commonly reported were fever (21), dyspnea (23), chills (21), headache (21), and nausea (19). Fourteen of the workers experienced the symptom of an unusual sweet or metallic taste in the mouth. Clinical signs were limited to wheezing or rales in eight patients. Leukocytosis and an increase in band cell forms were noted in 21 and 20 of 24 workers, respectively. The median time interval between exposure and onset of symptoms was five hours. None of three workers who spent less than one hour in the condenser became ill, whereas 25 of 26 of those who spent more than one hour became ill (p = .001). Five of 12 workers had urine copper levels in excess of 0.05 mg/l. To our knowledge, this is the first reported outbreak of MFF for which urinary copper levels have been measured.