Off-label use is the practice of prescribing a drug outside the terms of its official labeling. Worldwide, about 20% of the commonly prescribed medications are off-label, and the percentage increases in specific patient populations, such as children, pregnant women, and cancer patients. Off-label use is particularly widespread in oncology for many reasons, including the wide variety of cancer subtypes, the difficulties involved in performing clinical trials, the rapid diffusion of preliminary results, and delays in the approval of new drugs by regulatory organizations/agencies.The aim of this article is to describe the use of off-label drugs in oncology, with an emphasis on the role of the world's leading regulatory agencies and an assessment of current Italian legislation.Off-label drug utilization is essential in oncology when based on evidence. However, off-label drugs must be prescribed in accordance with existing national laws and only when the potential benefit outweighs the potential toxic effects.