OBJECTIVE: This open, randomized and blinded parallel-group multicenter study evaluated the efficacy of Actonel(r) (35 mg) plus calcium/vitamin D versus calcium/vitamin D alone for preserving bone mineral density (BMD) in postmenopausal women with Colles fractures.METHODS: Patients with a Colles fracture for seven days were randomized to receive either Actonel(r) (35 mg) once a week plus calcium/vitamin D (ACD group) or calcium/vitamin D alone (CD group). The patients were evaluated after 90 and 180 days of treatment.RESULTS: 59 ACD patients and 56 CD patients completed all the evaluations. At the end of the study, the BMD of the radius at the fracture location showed a negative change in the CD group (32.8%). The loss of BMD in the ACD group (20.8%) was slightly less than that in the CD group. There was a difference in the proportions of patients with BMD losses at the end of the study period in the two treatment groups, in favor of the ACD group, although this was not statistically significant. There was no significant difference in radiological identification of callus formation between the treatment groups. In the majority of the patients, the callus could be radiologically identified after 90 days.CONCLUSION: Postmenopausal women with Colles fractures who received risedronate sodium plus calcium/vitamin D did not show any significant difference in BMD loss in forearm fractures, in comparison with those who received calcium/vitamin D alone. Risedronate presented a tendency toward a protective effect regarding BMD loss due to immobilization. The time taken for fracture consolidation to be achieved was unaffected.