We describe three cases where biopsies from various tumors were guided by contrast enhancement of tumor perfusion. After i.v. administration of Levovist (Schering AG, Berlin, Germany), the tumors showed both hyper- and hypovascular areas. Biopsies from the latter showed marked necrosis or fibrosis. This may cause biopsies not being conclusive. To ensure fully diagnostic biopsies from irregular tumors we propose the biopsy to be performed from the most vascular part demonstrated by contrast enhancement. (C) 2000 Elsevier Science Ireland Ltd.