Bisphosphonates are widely used for the prevention and treatment of osteoporosis. Nonsteroidal anti-inflammatory drugs (NSAIDs) are also widely used among the older population group at high risk of fractures. NSAIDs have been shown to impact on bone turnover, and a recent reanalysis of a clinical trial of clodronate found that NSAID use at baseline abrogated any effect of clodronate on either bone density (BMD) or fracture risk. To determine whether NSAIDs influence the efficacy of other bisphosphonates, we have reanalyzed our 6-year randomized controlled trial of zoledronate in 2000 osteopenic postmenopausal women. NSAID use was reported at baseline in 38% of the cohort and anytime use was reported by 65%. The evolution of the zoledronate effects on BMD were almost identical whether or not women were using NSAIDs at baseline and were significant in both subgroups at all BMD sites (p < 0.0001). The significant reduction in the risk of fracture in those allocated to zoledronate (p < 0.0001) showed no interaction with baseline use of NSAIDs (p = 0.33) nor with NSAID use at any time during the study (p = 0.28). The odds of fracture were significantly reduced in both NSAID users and nonusers. We conclude that the present analysis provides no support for the suggestion that NSAIDs interfere with the efficacy of potent bisphosphonates in terms of their effects on bone density or fracture.