Background and purpose: Vertebral compression fractures (VCFs) are the most common fracture caused by osteoporosis. Percutaneous vertebroplasty (PVP) and kyphoplasty (PKP) are effective surgical interventions for reducing back pain, restoring body height, and improving quality of life. However, VCFs with nonosteoporotic etiologies, including unexpected malignancy, are sometimes difficult to distinguish preoperatively. This study investigated the incidence of unexpected malignancy in presumed osteoporotic VCFs undergoing PVP or PKP. Methods: A total of 127 patients with presumed osteoporotic VCFs undergoing PVP or PKP from December 2010 to August 2017 were retrospectively enrolled. Demographics, surgical method, magnetic resonance images, pathological report were collected. The incidence of unexpected malignancy in biopsy results was calculated. Results: A total of 161 vertebral biopsies from 127 patients undergoing 37 PVPs and 96 PKPs were examined. From these, two multiple myelomas and one metastatic liposarcoma were revealed through pathological examination. The incidence of unexpected malignancy was 2.4% (3/127). Conclusion: A biopsy is advisable during PVP and PKP in cases of presumed osteoporotic VCFs to exclude nonosteoporotic etiologies, specifically malignancy.