The use of replicating viruses for cancer therapy is attracting increasing interest. Numerous viruses are now being considered as potential cancer therapeutics, including the vaccine strain of measles virus (MV). The attenuated strain of measles readily lyses transformed cells, whilst replication and lysis are limited in normal human cells. It has a number of features which make it highly suitable for further development as an oncolytic agent, among them stability and a long history of safety in human use. These features are being combined with its ready potential for genetic manipulations to generate recombinant MVs with desirable therapeutic attributes. This review summarises the pre-clinical studies of the oncolytic efficacy of MV to date. Promising developments in MV engineering--such as re-targeting MV entry to specific cell types and enhancing its utility as a therapeutic agent by expression of non-viral proteins--as well as outstanding issues, such as the role of anti-MV immunity, are highlighted.