Serum lipid and lipoprotein concentrations were measured in 51 women with rheumatoid arthritis treated with both nonsteroidal and steroidal drugs and compared to a group of women with rheumatoid arthritis not receiving anti-inflammatory drugs and to a healthy control group. Significantly lower concentrations of total cholesterol and low density lipoprotein cholesterol were found in the rheumatoid patients on nonsteroidal or steroidal anti-inflammatory drugs, while no difference was found in high density lipoprotein cholesterol and triglycerides. In the group of rheumatoid patients who received no nonsteroidal or steroidal anti-inflammatory drugs, the triglyceride level was higher than in the control group, and that of HDL-C was lower. Total cholesterol and LDL-C levels were higher in the patients not on anti-inflammatory drugs than in patients receiving anti-inflammatory drugs. The results of this study suggest that hyperlipidemia is not one of the predisposing factors for coronary disease in patients with rheumatoid arthritis receiving anti-inflammatory therapy. Anti-inflammatory drugs may play a role in the regulation of serum lipids in patients with rheumatoid arthritis.