Purpose: In juvenile onset systemic lupus erythematosus (JoSLE), evidence for the association between vitamin D status, lupus activity, and bone health is very limited and not conclusive. The aim of this study was, therefore, to assess in JoSLE patients the possible relevance of vitamin D deficiency in disease and bone parameters. Methods: Fifty-seven JoSLE patients were initially compared to 37 age, race and body mass index (BMI) -matched healthy controls. The serum concentration of 25 hydroxyvitamin D (25OHD) was determined by radioimmunoassay. Patients with 25OHD deficiency ( 20 ng/mL) were compared to those with levels >20 ng/mL. Disease activity was evaluated by SLE Disease Activity Index (SLEDAI). Bone mineral density (BMD) and body composition (BC) were measured using dual-energy X-ray absorptiometry (DXA). Results: 25OHD levels were similar in patients and controls (21.44 AE 7.91 vs 22.54 AE 8.25 ng/mL, p ¼ 0.519), regardless of supplementation (65% of patients and none in controls). Thirty-one patients with 25OHD deficiency ( 20 ng/mL) were further compared to the 26 JoSLE patients with levels >20 ng/mL. These two groups were well-balanced regarding vitamin D confounding variables: age (p ¼ 0.