Frailty and osteoporosis are known to exacerbate each other. However, limited research is available on the shared pathophysiological factors contributing to osteoporotic fractures and frailty. This study aims to identify common factors associated with both the current frailty and the occurrence of incident vertebral fractures. A total of 912 postmenopausal Japanese women, 63.9 ± 10.0 yr of age (mean ± SD), were included in this study. Each participant's baseline frailty status was assessed using a questionnaire about the following 5 items: fatigue, resistance, ambulation, inactivity, and weight loss. A score of 3 or above indicated the prevalence of frailty. The participants were then followed up for an average of 10.5 ± 7.5 yr, during which 202 patients suffered incident vertebral fractures. The Cox proportional hazards model for incident vertebral fracture revealed that lumbar bone mineral density (hazard ratio [HR] 0.753,