Heparanase is an endo-beta-glucuronidase that degrades the glycosaminoglycan heparan sulfate, a major component of the extracellular matrix and basement membranes, and has been implicated in such processes as inflammation, angiogenesis and metastasis. The identification of inhibitors of heparanase is an attractive approach towards developing new therapeutics for metastatic tumours and chronic inflammatory diseases. This review focuses on heparanase inhibitors that have been isolated or synthesised to date. More recent developments in the understanding of heparanase structure and function that may ultimately aid in the future design of inhibitors with improved potency and specificity, are also discussed.