Caveolae exist at cell surfaces as caveolin-coated invaginations that perform transport and signalling functions influencing cell growth, apoptosis, angiogenesis and transvascular exchange. Caveolin could constitute a key switch in tumour development through its function as a tumour suppressor and as a promoter of metastasis, chemoresistance and survival. Targeting of drugs and gene vectors to tissue-specific proteins in caveolae allows selective delivery into vascular endothelial cells in vivo and might even improve direct access to solid-tumour cells. Therefore, caveolae seem to be rich in potential targets for cancer imaging and therapeutics.