Background: Patients with either osteoporosis or depression are prone to develop other diseases and require more medical resources than do the general population. However, there are no studies on health-related quality of life (HRQoL) and medical resource use by osteoporosis patients with comorbid depression. We conducted this study for clarifying it. Methods: This cross-sectional study from 2005 to 2010 (6 years) analyzed 9776 National Health and Nutrition Examination Survey (NHANES) patients > 40 years old. Each patient was assigned to one of four groups: osteoporosis-positive (+) and depression-positive (+) We used multivariate linear and logistic regression model to analyze the HRQoL and medical resource use between groups. Results: The O + /D + group reported more unhealthy days of physical health, more unhealthy days of mental health, and more inactive days during a specified 30 days. The adjusted odds ratios (AORs) of O + /D + patients who had poor general health (7.40, 95% CI = 4.80-11.40), who needed healthcare (3.25, 95% CI = 2.12-5.00), and who had been hospitalized overnight (2.71, 95% CI = 1.89-3.90) were significantly highest. Conclusions: Low HRQoL was significantly more prevalent in D + /O + patients. We found that depression severity more significantly affected HRQoL than did osteoporosis. However, both diseases significantly increased the risk of high medical resource use. expected to increase in the near future. In the developing world, 2% to 8% of men and 9% to 38% of women had osteoporosis [4].An association between major depressive disorder (MDD) and osteoporosis has been reported: patients with MDD apparently have significantly lower bone mineral density (BMD) [5]. Possible factors of reduced BMD in depression patients are the hypothalamic-pituitary-adrenal (HPA) axis: cortisol, leptin, and immune factor levels; cytokine, vitamin D, and parathyroid hormone levels; gender, lifestyle factors, the effect of antidepressants on BMD, osteoporotic fractures, and other comorbid psychiatric conditions [6]. Depression may increase serum cortisol level via activating the hypothalamic corticotropin-releasing hormone neuron. Hypercortisolemia is considered to be a destructive factor for bone health [6]. Depressed patients may have elevated leptin levels, which cause bone loss and inhibits bone formation via activation of sympathetic systems [7,8]. Depression is associated with immune dysregulation and increased oxidative stress, which stimulates HPA axis and results in hypercortisolemia [9,10]. Besides, depression is associated with lower vitamin D and increased parathyroid hormone levels, which may impact bone remodeling [11]. Antidepressants may interfere with sex hormone production such as androgen, which may decrease bone mass and increase risk of orthostatic hypotension, falls and bone fractures [12][13][14]. The incidence rate of depression or anxiety in women with osteoporosis was 46.8 per 1000 person years in the USA [15]. One study utilized data from US households civilian population from 2007...