BACKGROUND: Osteoporotic vertebral fractures (VFs) often go unrecognised in both healthy individuals and in pathological conditions. Few data exist on VFs in patients hospitalised in Internal Medicine Units (IMUs), who often suffer from multiple concomitant chronic disorders. AIM OF THE STUDY: This multicentre cross-sectional study was aimed at assessing the prevalence of VFs in an unselected population of patients referring to IMUs. Correlations between VFs and the main coexisting diseases were also investigated. METHODS: Information on demographic, clinical and laboratory findings, and on the presence of known risk factors for osteoporosis was recorded. The Genant's semi-quantitative method was used to evaluate, in a central reading centre, the presence and severity of VFs in the thoracic and lumbar spine. RESULTS: A cohort of 995 patients was evaluated. At least one VF of any grade was found in 47.5% of patients, with similar prevalence between females (48.1%) and males (46.7%). Older age, chronic obstructive pulmonary disease, and previous diagnosis of osteoporosis showed a significant association with VFs in multivariable analysis. However, 79.7% of the VFs were observed in patients without previous diagnosis of osteoporosis. Moreover, a VF of grade 2 or greater was found in 20.8% of patients. CONCLUSIONS: Fragility VFs is a very frequent finding in patients hospitalised in IMUs. Consequently, more attention should be devoted in this clinical setting to this comorbidity, which is known to be an additional factor for mortality and, when localised in the thoracic part of the spine, may negatively influence a concomitant respiratory insufficiency.