The arguments for a choice between a large or fine needle in the diagnosis of tumors are still unclear. This paper reviews the advantages and disadvantages of large-needle biopsy and fine needle aspiration. Reports indicate that although the procedures have the same diagnostic efficacy, the risk of tumor seeding is far higher following large-needle biopsy. For this reason it should be avoided for the diagnosis of cancer. The risk of tumor seeding after fine needle aspiration may be reduced by performance through a cover of normal parenchyma, by maintaining suction during withdrawal of the needle and by examining samples for quality during the procedure.