Malondialdehyde (MDA) levels in the serum were estimated by MDA-TBA (Thiobarbituric Acid) spectro colorimetric assay method in 23 rheumatoid arthritis (RA) patients and were compared with those in 18 healthy subjects. It was found that the mean levels of MDA (265.15 +/- 68.8 n moles/100 ml) in patients with RA were found to be significantly elevated when compared to the mean of that of controls (128.76 +/- 37.8 n moles/100 ml). This study reveals that MDA assessment appears to be a sensitive marker of inflammation in this chronic auto immune disorder and would help in understanding the nature of inflammatory damage at a cellular level.