BACKGROUND: Long-term treatment with glucocorticoids can induce bone loss and increase fracture risks. AIM: To compare the efficacy of a 12-month treatment between alfacalcidol and menatetrenone in preventing bone loss in children treated with long-term glucocorticoids. PATIENTS AND METHODS: Twenty children on a stable dosage of glucocorticoids were randomly divided into two groups (alfacalcidol or menatetrenone). Each group received the assigned treatment along with 400 mg of elemental calcium daily for 12 months. Patients receiving medications affecting bone metabolism or patients with impaired kidney function were excluded. Bone density parameters, including lumbar spine bone mineral content (BMC), bone mineral density (BMD), and BMD Z-score were assessed by dual-energy X-ray absorptiometry at baseline and at 12-month follow-up. Bone mineral apparent density (BMAD) was calculated as a size-adjusted measurement of BMD in growing children. Baseline characteristics and bone density parameters were similar between both groups. RESULTS: After 12 months, BMC and BMD were significantly increased from baseline in both groups, but did not differ between the groups. The BMD Z-score at 12-month follow-up was significantly decreased from baseline in the menatetrenone group. BMAD was significantly increased from baseline in the alfacalcidol group. CONCLUSIONS: Administration of long-term glucocorticoids in children justifies an intervention to preserve bone mass. Calcium supplementation along with alfacalcidol can prevent further bone loss to a greater extent than menatetrenone in this group of patients.