Fasting cholesterol, triglyceride, low density lipoprotein cholesterol, high density lipoprotein cholesterol, apoprotein AI, and apoprotein B were measured in 64 patients with systemic lupus erythematosus to assess the risk factors for vascular disease. The relation between the lipid profile, steroid treatment, the presence of anticardiolipin antibodies, and the prevalence of vascular disease was examined. Raised concentrations of triglyceride and apoprotein B were seen in those patients treated with more than the equivalent of 10 mg prednisolone a day in the six months before testing. An increase in vascular disease was found only in the subgroup of patients with increased triglycerides who also expressed anticardiolipin antibodies. This study confirms the association between treatment with high doses of steroids in lupus and the development of an atherogenic plasma lipid profile. The presence of anticardiolipin antibodies compounds the risk of developing vascular disease.