VLDL (200μg Protein/ml)was incubated with MΦ for 24 and 48 hours. The TBARS in VLDL after incubation for 24 and 48 hrs were 10.04±0.77 and 11.25±0.53nmol/mg protein respectively, which were much higher than that of controls (4.60±0.56,7.95±0.66 respectively). The MΦ modified VLDL migrated faster than the controls on agarose electrophoregram. In conclusion, VLDL could be oxidatively modified by MΦ in vitro. It suggests VLDL might be oxidited in Vivo. VLDL is also susceptible to oxidative modification by Cu²⁺ in vitro resulting in an increase in electrophoretie mobility and TBARS in the lipoprotein. Cu²⁺—Ox—VLDL had the potential ability to increase MC adherence to EC. The effects were concentration dependent. The percentage of MC adherence in n—VLDL group was much less than that in Ox—VLDL group (p<0.001). It suggests that Ox—VLDL plays an important role in MC adherence to EC.