Aim To investigate malondialdehyde-modified (MDA) low-density lipoprotein (LDL), its immune complexes (LDL-IC) and blood lipid levels in patients with rheumatoid arthritis (RA), and to explore the mechanism of high incidence from cardiovascular disease in patients with RA. Methods 55 patients with RA, 13 of which had cardiovascular disease (CAD), 42 of which had simply RA, and 60 healthy controls were randomly chosen. Plasma MDA-LDL and its immune complexes (LDL-IC) levels were determined by enzyme linked immunosorbent assay (ELISA). Blood lipid levels and inflammatory markers were also studied. All data was subjected to statistical analysis. Results Compared with the control, plasma lipids and apolipoproteins levels in patients with RA remained unchanged, except that apolipoprotein B levels increased in RA patients (P<0.05); meanwhile no difference was found in plasma lipids and apolipoproteins concentrations between simple RA patients and RA patients with CAD. MDA-LDL level in RA with CAD, simple RA and control were 187.81±90.89 mg/L, 102.01±57.73 mg/L and 32.65±27.00 mg/L, respectively. LDL-IC level in the three groups were 2.58±1.69 AU, 1.87±0.74 AU and 1.21±0.38 AU, respectively. Compared with the control, MDA-LDL and LDL-IC levels increased in simple RA patients and RA patients with CAD (P<0.01), furthermore, MDA-LDL and LDL-IC levels in RA patients with CAD were both found significantly higher than those in simple RA (P<0.01 or 0.05). LDL-IC level was found related with C-reactive protein (r=0.301, P=0.026), and MDA-LDL level tended to be related with erythrocyte sedimentation rate (r=0.263, P=0.057). Conclusions MDA-LDL and LDL-IC were both increased in RA patients, and may play an important role in atherocslerosis.