852 Japanese patients with involutional osteoporosis were randomized to receive 75 mg oral risedronate once-monthly or 2.5 mg oral risedronate once-daily, with the purpose of comparing the efficacy, tolerability, and safety of both treatment options. Upon analysis, results indicated that 75 mg risedronate tablets taken once a month achieved similar bone mineral density and fracture rates compared to 2.5 mg risedronate tablets taken once a day. Urinary NTX/CRN and CTX/CRN bone markers decreased significantly in both groups, but resulted in a more pronounced reduction in the 2.5 mg once-daily risedronate group, while acute phase reaction adverse events were higher in the 75 mg once-monthly risedronate group.