BACKGROUND: Postmenopausal osteoporosis constitutes a major health problem in Norway, and is associated with significant morbidity and mortality. Bisphosphonates are the first line treatment for the management of osteoporosis. Still, many aspects concerning bisphosphonate treatment remains inadequately documented; including whether there are significant differences between the bisphosphonates regarding fracture-preventing effect. OBJECTIVE: To compare the fracture-preventing effect of the four most commonly used bisphosphonates in Norway on postmenopausal osteoporosis. METHOD: This project is a systematic literature review, based on a literature search in PubMed. This database was searched for systematic reviews and meta-analyses published the last ten years concerning the use of alendronic acid, ibandronic acid, risedronic acid and zoledronic acid and their effect on the most commonly occurring osteoporotic fractures; vertebral, hip and wrist fractures. RESULTS: After a systematic selection based on pre-specified criteria of inclusion and exclusion, five systematic reviews were identified. The results from these five reviews show that all four bisphosphonates have significant preventive effect on vertebral fractures compared to placebo. The same goes for the preventive effect on hip fractures, with the exception of ibandronic acid. Alendronic acid is the only bisphosphonate which is proven to have preventive effect on wrist fractures compared to placebo. Indirect comparison, based on mixed treatment comparison metaanalysis (MTC), shows that zoledronic acid is more effective in preventing vertebral fractures than the other three bisphosphonates, and that there are no significant differences between the bisphosphonates in the preventive effect on hip fractures. None of the five included systematic reviews have undertaken an MTC concerning the effect on wrist fractures; hence it remains unclear whether there are significant differences between the bisphosphonates regarding preventive effect on this fracture type. CONCLUSION: Of the four most commonly used bisphosphonates in Norway for postmenopausal osteoporosis, zoledronic acid is proven to be more effective than alendronic acid, ibandronic acid and risedronic acid in preventing vertebral fractures. Moreover, zoledronic acid has the highest probability of being the most efficacious bisphosphonate regarding the prevention of vertebral and hip fractures, in addition to the compound outcome “any fracture”.