OBJECTIVE--To evaluate bone mineral density (BMD) in premenopausal patients with systemic lupus erythematosus (SLE). METHODS--We measured BMD by dual energy x ray absorptiometry at lumbar vertebrae L2-4 and at the right femoral neck in 74 premenopausal white patients (mean age 30.8 years) with SLE who were receiving glucocorticoid therapy, and in a control group. RESULTS--The mean cumulative dose of prednisone was 32.5 (SD 28) g. The mean dose at the time of absorptiometry was 13.7 (6.9) mg. BMD was significantly reduced at the spine and at the femoral neck in SLE patients when compared with the control group: L2-4 = 0.943 (0.1) g/cm2 v 1.038 (0.1) g/cm2 (p < 0.001); femoral neck = 0.766 (0.09) g/cm2 v 0.864 (0.1) g/cm2 (p < 0.001). Nine patients (12.1%), but none of the control group, had a BMD less than the reference range. CONCLUSION--BMD in premenopausal patients with SLE was less than that in a control group and less than the reference range of values defining the presence of osteoporosis in 12.1%. We did not find a relationship between BMD and either cumulative or baseline dose of corticosteroid therapy.