Lipid, lipoprotein, and apolipoprotein effects of hydroxychloroquine were studied in 18 female patients with systemic lupus erythematosus (SLE) with mild or inactive disease. Patients were case matched (200-400 mg hydroxychloroquine daily vs no hydroxychloroquine) on several factors including daily corticosteroid dose in this cross sectional study. All had normal menstrual cycles; none smoked, used alcohol, were taking lipid altering medications or had other concurrent diseases. Patients taking hydroxychloroquine had 35-54% lower total triglyceride, VLDL-triglyceride, LDL-triglyceride, HDL-triglyceride, VLDL-cholesterol, and apolipoprotein CIII levels (p < 0.03). These results are encouraging in that hydroxychloroquine, in addition to being useful for alleviating the primary symptoms of SLE, may also be useful for ameliorating the adverse effects of corticosteroid therapy on triglyceride-rich lipoprotein metabolism.