We measured the concentrations of polychlorinated dizenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and non-ortho-coplanar polychlorinated biphenyls (Co-PCBs) in blood collected from 279 Yusho patients and 92 Yusho-suspected persons living in Japan in 2002, 269 Yusho patients and 74 Yusho-suspected persons living in Japan in 2003 and 128 normal controls living in Fukuoka Prefecture, and compared with the concentrations of these compounds among the groups. The total TEQ concentrations of PCDDs, PCDFs, and Co-PCBs in the blood of Yusho patients were 3.6 times and 3.3 times higher than those in the normal controls in 2002 and 2003, respectively. In the case of Yusho-suspected persons, the concentrations were 1.1 times and 1.0 times higher in 2002 and 2003, respectively. Among the TEQ concentrations of PCDDs, PCDFs, and Co-PCBs, the concentrations of PCDFs in the blood of Yusho patients were 10.3 times and 9.4 times higher than those of the normal controls in 2002 and 2003, respectively, whereas the concentrations of PCDDs and Co-PCBs in blood were identical in Yusho patients, Yusho-suspected persons and normal controls. Yusho patients indicated the highest concentrations ratio of PCDFs to the total TEQ concentrations. Moreover, of the PCDFs congeners for Yusho patients, the concentrations of 2,3,4,7,8-PeCDF were about 11.0 times and 10.1 times higher in 2002 and 2003 than those in normal controls. These results indicated that Yusho patients have a much higher concentration of 2,3,4,7,8-PeCDF in their blood than do unaffected persons even though over 34 years have passed since the outbreak of Yusho.