['Although there is increasing in bone metabolism in patients with rheumatic disorders, few data exist on bone mineral density (BMD) in children with rheumatic disorders or on the association of BMD with disease-related variables. We determined BMD in Iranian children with systemic lupus erythematosus (SLE) and juvenile rheumatoid arthritis (JRA) to evaluate the relationship between disease-related variables and BMD.', 'Twenty patients (13 girls and 7 boys) with SLE (n=15) and JRA (n=5) with a mean age of 13.10+/-3.29 years (range, 6-17 years), attending a pediatric rheumatology clinic and 20 healthy controls (matched for age and sex with each patient) were enrolled in a cross-sectional study between 2001 and 2003. BMD (g/cm(2)) of the femoral neck (BMD-F) and lumbar vertebrae (BMD-L) were measured by dual energy X-ray absorptiometry (DEXA). The correlation between BMD and cumulative dose of steroids, daily dose of steroid, disease duration, disease activity, height, weight, and age was investigated.', 'BMD in the patients (BMD-F=0.72+/-0.15, BMD-L=0.70+/-0.19) was significantly lower than controls (BMD-F=0.95+/-0.17, BMD-L=0.98+/-0.20, P=<0.001). The severity of descreased BMD was more prominent in lumbar vertebrae than the femoral neck (P=0.04). None of the variables were consistently related to a decrease in BMD.'] Do bone mineral density in children wth systemic lupus erythematosus and juvenile rheumatoid arthritis?