The aim of this study was to determine the prevalence and risk factors for low bone mineral density (BMD) in women with systemic lupus erythematosus (SLE). A cross-sectional study was conducted among 100 pre-menopausal patients with SLE. Patients were evaluated using a questionnaire about the following variables: age, disease duration, disease activity, chronic disease damage, cumulative corticosteroid dose, and history of fracture. Lumbar spine and hip measurements of BMD were performed by dual absorptiometry. Univariate and multivariate statistical analyses were used to assess the relationship between risk factors and BMD. The mean age was 32.8 +/- 8.7 years, and the median duration of SLE was 73.2 +/- 65 months. The mean cumulative corticosteroid dose was 20.0 +/- 21.3 g. The mean BMD was 1.09 +/- .18 g/cm(2) in the lumbar spine and 1.0 +/- .14 g/cm(2) in the hip. Osteopenia was present in 40% of patients and osteoporosis in 5%. In the multiple regression analysis, low BMD in the lumbar spine was associated with chronic disease damage and low body mass index (BMI). Low BMD in the hip was associated with cumulative corticosteroid dose and low BMI. Chronic disease damage, low BMI, and cumulative corticosteroid dose are risks factors for low BMD in pre-menopausal SLE patients. Osteopenia was found in 40% of patients, while osteoporosis was found in only 5%.