A complex network of chemokines and their receptors influences the development of primary tumours and metastases. New information about the biological role of chemokines in these processes is providing insights into host–tumour interactions, such as the role of the leukocyte infiltrate, and into the mechanisms that determine the metastatic potential and site-specific spread of cancer cells. Chemokine-receptor antagonists are showing promise in animal models of inflammation and autoimmune disease. Could manipulating the local chemokine network have therapeutic benefits in malignant disease?