Although biopsies are a key step in the diagnosis of bone tumors, they are often still referred to as a minor intervention which can be carried out by any surgeon as an outpatient procedure or quickly carried out between other more important tasks. A biopsy should, however, be regarded as the final part of the diagnostic procedure preceded by careful evaluation of the clinical course and analysis of the required imaging studies. Although the biopsy procedure seems technically simple to perform, an incorrectly performed biopsy can become an obstacle to correct tissue analysis (sampling error) and adequate tumor resection and may reduce the patient's chances of survival. The principles by which an adequate and safe biopsy of bone tumors should be planned and executed are reviewed and the surgical approaches to different anatomical locations are presented.