AbstractAn outbreak of PCB poisoning through consumption of the contaminated rice oil in Central Taiwan was investigated. It covered four counties and there were 1,843 cases by the end of 1980. The highest frequency of incidence occurred during the period from March to July 1979. Severity of clinical manifestations was graded, most patients exhibiting mild or moderate severity. The major age group of the outbreak was between 11 to 20 years old. Most of the victims were students and factory workers. The amount of PCB intake in each victim was estimated to be 0.7 to 1.84 gm and the latent period from the time of intake to the onset of clinical manifestations was approximately three to four months. The patients' blood PCB concentrations ranged from 3 to 1,156 ppb. In 613 patients, 44.37% (272 patients) had PCB levels of 51–100 ppb, and 27.57% (169 patients) had levels over 100 pp