Skin symptoms of yusho and their subsequent change were described. In the early stage, skin eruptions were the most prominent features of yusho. Acneform eruptions and pigmentation were most conspicuous. With the passage of time, these symptoms have improved considerably and most patients have very slight eruptions now, except for the severely intoxicated group. In the analysis of polychlorinated biphenyl (PCB) in the blood, the severely intoxicated group with intense skin symptoms showed pattern A--a typical yusho-specific pattern. The blood PCB patterns of each patient were stable, with no alteration after many years; on the other hand, the blood PCB concentrations have diminished year by year.