To evaluate chronic effect of PCBs on laboratory findings, peripheral blood cells and biochemical parameters were studied in 74 patients with Yusho in 1994. Serum level of triglyceride was elevated in 21 cases (28.4%) of these patients. Serum triglyceride levels showed statistically significant correlation with body mass index (Quetelet Index) and blood PCB concentration. We conclude that hypertriglyceridemia in patients with Yusho is not frequent and it may be associated with both obesity and blood PCB concentration.