An outbreak of poisoning caused by ingestion of rice bran oil which was accidentally contaminated with polychlorinated biphenyls (PCBs) broke out in Taiwan in February 1979. Diagnosis, management, and follow-up of the patients were performed at special clinics, and subjective symptoms and cutaneous changes such as peculiar acneform eruptions and pigmentation were recorded. The patients were divided into six age groups of both essex, and the body surface of the patients was divided into 12 sections according to the nature of skin. The prevalence of each type of cutaneous change was proved statistically by the chi-square test. The examination of the immune system function in the patients at 1 year revealed: decreased concentration of IgM and IgA but not of IgG; decreased percentage of total T-cells, active T-cells, and helper T-cells, normal percentage of B-cells and suppressor T-cells; suppression of delayed type response to recalling antigens; enhancement of lymphocyte spontaneous proliferation; and enhancement of lymphocyte proliferation with PHA, PWM, and PPD stimulation but not ConA. Follow-up studies 3 years later showed decreased blood PCB levels; some improvement of subjective symptoms and cutaneous changes; recovery of skin testing response to PPD; normal percentage of total T-cells and increased percentage of suppressor T-cells; and enhancement of lymphocyte proliferation spontaneously or under the stimulation of various mitogens.