Objective: Osteoporosis is charnacterized by an increased rate of bone turnover and a reduciton of bone mass. The nitrogen-containing bisphospho nates, alendronate and risedronate, have been shown to increase bone mineral density(BMD) at the spine and hip. The current analyses were performaed in order to compare BMD change and newly developed oseoporotic vertebral compression fractures(OVCFs) after bisphosphonate therapy.  Methods: There was a total of 171 patients who have been treated with one of bisphophonates for the treatment of osteoporosis, Inclusion criteria for this study were; (1) patients who had the diagnosis of OVCF,(2) patients who had taken medication for 6 months, and (3) patients who had been followed for months or longer. Patients who met all inclusion criteria(97 pateints) were divided into 2 groups : alendronate group(74 patients) and risedronate group (20 patients). BMD and spine x-ray were obtained at baseline, 6 months, and when new symptoms develop or when previous symptoms were aggrevated.  Results: During the follow-up period, 3 patients developed new OVCF(4.1%) and 9 patients showed aggravation of BMD scores(12.2%) in alendrontae group. In risedronate group, one patient developed new OVCF (5%) and one patient aggravated BDM score(5%). Statistically,however, there were no meanigful differences(OVCF; p=0.861, BMD score; p=0.253).  Conclusion: In our study, there were no differnces in new OVCF and BMD aggrabation in these groups. A randomized controlled trial with larger population and longer follow up period will be needed before making and justification can be made.