Recent studies have shown that systemic lupus erythematosus (SLE) is associated with a loss of trabecular bone. However, these changes have not been not described in patients with SLE at the time of diagnosis. To investigate the markers of bone metabolism 20 female patients with a recently manifested clinical picture of SLE were selected. All patients included in this study met the ARA criteria (for classification) of SLE. For comparison, 35 female patients with SLE, which had previously manifested itself and which had been treated with glucocorticoids, were included in a second group. A control group (III) consisting of 20 healthy individuals of the same age was formed to compare the results obtained. Test parameters comprised both serum levels of osteocalcin (OC) as the marker for bone formation and crosslinks excretion (CE) in urine as a specific marker for bone resorption. The bone density (BMD) was examined by dual energy X-ray absorption (DEXA) of the vertebral column (L2-L4), femoral neck, Ward's triangle and trochanter. The patients under study received either no medication or nonsteroidal antirheumatic drugs. The BMD of the vertebral column was significantly lower than expected in SLE-afflicted subjects of group II when compared with the age-matched normal female controls. The reduction of BMD in female patients with SLE was related to the significantly increased excretion of urinary pyridinoline, to hypoparathyroidism, and to the decrease in serum OC. Bone loss in women with fresh manifestation of SLE (I) increases to a degree similar to that of patients in group II. Lowered BMD predicts an increased risk for bone fractures. Therefore, female premenopausal SLE patients should be monitored for osteoporosis.