To determine the effects of high dose methylprednisolone (HDMP) pulses on bone mineral density (BMD) in patients with multiple sclerosis (MS), we studied 25 MS patients who received regular pulses of HDMP as well as pulses of HDMP for relapses, 18 MS patients who received HDMP at the same dose schedule only for relapses, and 61 healthy controls. We measured BMDs at lumbar spine and femoral neck and we assessed biochemical markers of bone metabolism and turnover. The average lifetime dosage of MP was 75.4 (SD 11.9) g in the pulsed HDMP group and 28.6 (SD 18.3) g in the HDMP for relapses group (P < 0.0001). Two MS patients (4.7%) and four controls (6.6%) had osteoporosis (P = NS), whereas 25 patients with MS (58.1%) and 21 controls (34.4%) had osteopenia (P = 0.016). BMDs measured at lumbar spine and femoral neck and biochemical indices of bone metabolism did not differ in MS patients and controls. BMD measures were not associated with lifetime methylprednisolone dosage. In partial correlation analysis, controlling for age, gender and menopausal status there was a significant inverse correlation between BMD at femoral neck and Expanded Disability Status Scale (EDSS) score (r = -0.31, P = 0.05). In conclusion, treatment with repeated HDMP pulses was not associated with osteoporosis in patients with MS who participated in a trial of methylprednisolone. However, osteopenia was observed more frequently in MS patients than healthy controls. Our data are reassuring, as them suggest that repeated pulses of methylprednisolone do not result in substantially increased risk of osteoporosis in MS patients. Moreover, osteopenia was found only in patients treated for relapses, who had a significantly higher EDSS score than patients in the HDMP group, suggesting that decreased mobility may contribute to bone loss more than corticosteroid use. BMD should be monitored in patients with MS, regardless of the use of methylprednisolone.